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.rs
\v | 5i'
.sp 1P
.ce 1000
\v'3P'
SECTION\ 7
.ce 0
.sp 1P
.ce 1000
\fBTONES\ FOR\ USE\ IN\ NATIONAL\fR  |
\fBSIGNALLING\ SYSTEMS\fR 
.ce 0
.sp 1P
.sp 2P
.LP
\fBRecommendation\ E.180\fR 
.FS
This Recommendation is also included in the Series Q Recommendations under 
the number Q.35 (Fascicle\ VI.1) 
.FE
.RT
.sp 2P
.ce 1000
\fBTECHNICAL\ CHARACTERISTICS\ OF\ TONES\fR 
.FS
See
Supplement No.\ 2 at the end of this fascicle for
particular values of tone cadences and frequencies in actual use.
.FE
.EF '%	Fascicle\ II.2\ \(em\ Rec.\ E.180''
.OF '''Fascicle\ II.2\ \(em\ Rec.\ E.180	%'
.ce 0
.sp 1P
.ce 1000
\fBFOR\ THE\ TELEPHONE\ SERVICE\fR 
.ce 0
.sp 1P
.LP
\fB1\fR 	\fBGeneral\fR 
.sp 1P
.RT
.PP
Administrations are reminded of the advantages of standardizing
audible tones
as far as possible so that subscribers and operators may quickly recognize 
any tone transmitted of whatever 
origin
.FS
Recommendation\ E.181 specifies the information which could be given to 
users to facilitate recognition of foreign tones. 
.FE
.
.PP
Guidance on the application of tones and recorded announcements in
various situations is given in Recommendation\ E.182.
.PP
In considering the degree of standardization, the CCITT took
account of the nature of the various tones already in use. It was also
considered that Administrations introducing new tones would find it helpful
to know the preferred limits of cadence frequency and level.
.PP
Limits for 
tone cadences and frequencies
are set forth below,  all working tolerances being included in the limits.
.PP
Besides the limits applying to specifications, limits have been laid down 
for application to existing exchanges. 
.PP
These latter limits are herein called \fIaccepted\fR limits, while those 
for new equipment are called \fIrecommended\fR limits. 
.PP
The present Recommendation covers the case where audible tones are
applied within the network. However, the same frequencies and cadences 
are to be applied if, in the ISDN, the audible tones are generated at the 
terminal 
equipment.
.RT
.LP
.sp 2P
.LP
\fB2\fR 	\fBElectrical levels for tones\fR 
.sp 1P
.RT
.PP
For international purposes, the levels of the 
ringing tone
,
the
busy tone
, the 
congestion tone
, the 
special information
tone
and the 
warning
tone
have to be defined at a 
zero relative level point
at the
incoming (in the traffic direction) end of the international circuit.
.PP
The level of tones so defined must have a nominal value of \(em10\ dBm0. 
The recommended limits should be not more than \(em5\ dBm0 nor less than 
\(em15\ dBm0 measured with continuous tone. 
.bp
.PP
For the special information tone, a difference in level of 3\ dB is
tolerable between any two of the three frequencies which make up the tone.
.PP
For the power level of the 
dial tone
the point of reference is the local exchange, where the subscriber line 
is connected. In the existing 
networks the absolute power at the 2\(hywire access in the direction towards 
the subscriber station is normally in the range of \(em10\ dBm \(+- | \ 
dB. However, with 
respect to interference with 
multifrequency pushbutton (MFPB)
receivers
dial tone levels higher than \(em10\ dBm should be avoided.
.PP
\fINote\fR \ \(em\ The relative level of local exchanges in an analogue 
network is not fixed. For digital local exchanges the relative levels are 
given in 
Recommendation\ Q.517. A preferred level range of digital tone generators is
\(em8\ dBm0 to \(em3\ dBm0 corresponding with the above level range at 
the output of 
local exchanges.
.RT
.sp 2P
.LP
\fB3\fR 	\fBAcoustical levels for tones\fR 
.sp 1P
.RT
.PP
When tones are generated by a source within a network, e.g.,\ by a telephone 
exchange, the power level as perceived by the user will be influenced by 
the characteristics of the subscriber's line and the equipment between 
the source and the user's ear. 
.PP
Furthermore, tones can be generated within the user's equipment,
triggered by signals from the exchange. In these circumstances it is necessary 
to define the tone level in terms of the preferred range of sound pressure 
levels as heard by the listener.
.PP
Research has shown that the preferred listening level for information tones 
is substantially independent of room noise, circuit noise and tone 
cadence, but does vary over a range of tone frequencies. Figure\ 1/E.180 
shows the recommended sound pressure levels, with upper and lower limits 
of the 
recommended range, over a range of tone frequencies, based on these
experiments.
.RT
.LP
.rs
.sp 27P
.ad r
\fBFigure 1/E.180, p.332\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
It is emphasized that there is no one\(hyto\(hyone relationship between 
electrical and 
acoustical power levels
. What acoustic level will result from a given electrical level is dependent 
on various parameters such as the 
characteristics of the user's equipment.
.PP
It should be noted that the recommended sound pressure levels apply
only to the most common situation of a user listening via a telephone handset, 
held reasonably close to the ear so that normal \*Qear coupling loss\*U 
values 
apply.
.PP
When using a loudspeaking telephone or a headset, the preferred sound pressure 
level is generally lower than the recommended levels. 
.RT
.LP
.sp 2P
.LP
\fB4\fR 	\fBDial tone\fR 
.sp 1P
.RT
.PP
4.1
It is recommended that dial tone should be a continuous tone.
.sp 9p
.RT
.PP
4.2
It is recommended that dial tone should be:
.LP
	\(em
	\fIeither\fR a single frequency tone in the range 400\(hy450 Hz,
.LP
	\(em
	\fIor\fR a combined tone composed of up to three frequencies,
with at least one frequency in each of the ranges 340\(hy425\ Hz and
400\(hy450\ Hz. The difference between any two frequencies should
be at least 25\ Hz.
.LP
.PP
4.3
Recognizing the local nature of \*Qnormal\*U use of dial tone, as well 
as the technical and economic consequences and consequences on customer 
habits 
of changes in dial tone,
the full range of existing dial tones, including non\(hycontinuous tones as in
Supplement No.\ 2 at the end of this fascicle, are
considered acceptable. However, when adopting a new single frequency dial 
tone, Administrations are recommended to use 425\ Hz. 
.sp 9p
.RT
.PP
4.4
Where digital tone generation is applied, the frequencies for
dial tone should be the same as those recommended for analogue generated 
tones (see Annex\ A). 
.PP
4.5
In order to prevent interference of harmonics or spurious
components of the dial tone with the frequencies recommended for pushbutton
telephone sets in Recommendation\ Q.23 and the MFPB signal reception specified 
in Recommendation\ Q.24, the maximum permissible power level of harmonics 
or 
quantizing noise of the dial tone has to be limited in a suitable way,
depending on the specific characteristics of the implementations of the dial
tone generator and the MFPB receivers within the same exchange. Examples of
such limitations for the dial tone generator are given in Annex\ B.
.LP
.PP
\fINote\fR \ \(em\ In cases of digital generation of the dial tone, the
quantizing noise is composed of a number of spectral lines which depend 
on the number of samples in the generating pattern. In order to reduce 
the amplitude of the quantizing components, the number of samples should 
be chosen 
sufficiently high, thus spreading the quantizing distortion power more 
evenly over the whole spectrum. 
.sp 2P
.LP
\fB5\fR 	\fBRinging tone\fR 
.sp 1P
.RT
.PP
5.1
Ringing tone is a slow period tone, in which the tone period is shorter 
than the silent period. 
.sp 9p
.RT
.PP
The \fIrecommended\fR limits for the tone period (including
tolerances) are from 0.67 to 1.5 seconds. For existing exchanges, the
\fIaccepted\fR upper limit for the tone period is 2.5\ seconds.
.PP
The \fIrecommended\fR limits for the silent period separating two tone
periods are 3\ to 5\ seconds. For existing exchanges, the \fIaccepted\fR 
upper limit is 6\ seconds. 
.PP
The first tone period should start as soon as possible after the
called subscriber's line has been found.
.PP
Figure 2/E.180 shows the recommended and accepted limits for the
ringing tone periods.
.bp
.RT
.LP
.rs
.sp 25P
.ad r
\fBFigure 2/E.180 p. 333\fR 
.sp 1P
.RT
.ad b
.RT
.PP
5.2 
The ringing tone cadence should be similar to the cadence used for
applying ringing current to the called subscriber's telephone set, but
these two cadences need not be synchronized. The electrical parameters
of the ringing current must be evaluated by the Administration concerned to
prevent shock hazard.
.PP
5.3
The recommended frequency for the ringing tone is between 400 and
450\ Hz. The accepted frequency should be not less than 340\ Hz, nor more than
500\ Hz. Frequencies between 450 and 500\ Hz in the accepted frequency range
should, however, be avoided. Administrations adopting a new single frequency
ringing tone are recommended to use\ 425\ Hz.
.PP
The ringing tone frequency may be modulated by a frequency
between 16\ and 100\ Hz, but such modulation is not recommended for new
equipment. If the accepted frequency is more than 475\ Hz, no modulation by a
lower frequency is allowed.
.PP
5.4
Where digital tone generation is applied, the frequency for
ringing tone should be the same as that recommended for analogue generated
tones (see Annex\ A).
.sp 2P
.LP
\fB6\fR 	\fBBusy tone\fR \fBand\fR 
\fBcongestion tone\fR 
.sp 1P
.RT
.PP
6.1
The (subscriber) busy tone and the (equipment or circuit group) congestion 
tone are \fIquick\fR period tones in which the 
tone period
is
theoretically equal to the 
silent period
. The total duration of a
complete cycle (tone period\ \fIE\fR \ + silent period\ \fIS\fR ) should 
be between 
300 and 1100\ milliseconds.
.sp 9p
.RT
.PP
The ratio \fIE\fR /\fIS\fR of the tone period to the silent period should 
be between 0.67 and 1.5 (\fIrecommended\fR values). 
.PP
For existing exchanges, or for tones to be used in a special way, it is 
\fIaccepted\fR that the tone period may be up to 500\ milliseconds shorter 
than the silent period (\fIE\fR \ \(>="\ \fIS\fR \ \(em\ 500\ milliseconds). 
In no circumstances should 
the tone period be shorter than 100\ milliseconds.
.bp
.PP
Figure 3/E.180 shows the recommended and the accepted areas for the
busy tone and the congestion tone periods.
.RT
.LP
.rs
.sp 32P
.ad r
\fBFigure 3/E.180, p. 334\fR 
.sp 1P
.RT
.ad b
.RT
.PP
6.2
The busy tone (of the called subscriber) and the congestion
tone (of switching equipment or circuit groups) can be identical or almost
identical, providing that this does not create any serious problems for the
network and does not cause the subscriber to become confused. However, a
distinction between these two tones is desirable:
.LP
	\(em
	to allow Administrations to assess the quality of service,
.LP
	\(em
	for the convenience of experienced subscribers.
.LP
.PP
6.3
Where a distinct congestion tone is used, it is recommended
that:
.sp 9p
.RT
.LP
	a)
	 the same \fIfrequency\fR  | should be used for the busy tone and the 
congestion tone; 
.LP
	b)
	 the busy tone should have a slower cadence than the congestion tone, 
but both cadences should be within the limits mentioned in 
\(sc\ 5.1 above.
.PP
6.4
The \fIrecommended\fR  | frequency for the busy tone and for the
congestion tone must be between\ 400 and 450\ Hz. The \fIaccepted\fR frequency 
must not be less than 340 nor more than 500\ Hz. Frequencies between 450 
and 500\ Hz in the accepted frequency range should, however, be avoided. 
Administrations 
adopting a new single frequency for busy and congestion tones are recommended 
to use 425\ Hz. 
.bp
.sp 9p
.RT
.PP
6.5
Where digital tone generation is applied, the frequency for busy
and congestion tones should be the same as that recommended for analogue
generated tones (see Annex\ A).
.sp 2P
.LP
\fB7\fR 	\fBSpecial information tone\fR 
.sp 1P
.RT
.PP
7.1
The special information tone is provided for all cases in which
neither the busy nor the congestion tone can give the required information 
to the calling subscriber in the case of call failure. There are three 
ways in 
which it may be used:
.sp 9p
.RT
.LP
	a)
	when in special cases no provision is made for recourse either
to a recorded announcement or to an operator, the equipment at the
point which the calls have reached must:
.LP
	1)
	\fIeither\fR  | connect the special information tone to the call,
.LP
	2)
	\fIor\fR  | preferably, if technically available,
send an appropriate backward signal such that connection to
the special information tone will be made by equipment which
is nearer to the caller;
.LP
	b)
	 when the call is connected to a recorded voice machine; the tone is then 
given during the silent intervals between transmissions 
of the announcement;
.LP
	c)
	under arrangements made at manual positions serving lines
which have been abnormally routed so that by operating a key the
operators may send the special information signal when, for
example, the calling subscriber fails to understand the
operator.
.PP
When the special information tone is applied with or without a
recorded announcement, it should be recognized that customers may refer 
to an operator if they fail to understand the meaning of the recorded announcement 
and/or the special information tone.
.PP
7.2
The special information tone has a tone period theoretically
equal in length to the silent period.
.sp 9p
.RT
.PP
\fITone period\fR \ \(em\ The tone period consists of three successive 
tone signals, each lasting for 330\ \(+-\ 70\ milli 
seconds. Between these tone signals there may be a gap of up to 30\ milliseconds. 
.PP
\fISilent period\fR \ \(em\ This lasts for 1000\ \(+-\ 250\ milliseconds.
.RT
.LP
.PP
7.3
The frequencies used for the three tone signals are:
950\ \(+-\ 50\ Hz; 1400\ \(+-\ 50\ Hz; 1800\ \(+-\ 50\ Hz, sent in that order.
.sp 9p
.RT
.sp 2P
.LP
\fB8\fR 	\fBWarning tone to indicate that a conversation is being\fR 
\fBrecorded\fR 
.sp 1P
.RT
.PP
Where a conversation is being recorded at a subscriber's station, it is 
recommended that the Administration require the use of 
a warning tone to indicate that the conversation is being recorded. When 
such a tone is applied, it is recommended that: 
.RT
.LP
	a)
	it consists of a 350\(hy500 ms pulse every 15\ \(+-\ 3 seconds of
recording time, and
.LP
	b)
	the frequency of the tone should be 1400 Hz\ \(+-\ 1.5%.
.sp 2P
.LP
\fB9\fR 	\fBPayphone recognition tone\fR 
.sp 1P
.RT
.PP
9.1
Where Administrations see the necessity of application of a
payphone recognition tone in order to allow operators to recognise that 
a call originates at a payphone station or that the called number belongs 
to a 
payphone station it is recommended to use a payphone recognition tone.
.sp 9p
.RT
.LP
.PP
The application of the tone will depend on the operational
requirements of individual Administrations, e.g.,\ in some cases the tone 
will only be required on an incoming call to the payphone, whilst in others 
there 
may be a requirement for the tone to be present on originating calls and
throughout the period of the call.
.bp
.PP
9.2
The tone is a combination of two frequencies \fIf\fR\d1\uand
\fIf\fR\d2\uin the range:
.sp 9p
.RT
.LP
	\fIf\fR\d1\u:\ 1100\(hy1750 Hz
.LP
	\fIf\fR\d2\u:\ \ 750\(hy1450 Hz
.LP
with the ratio: \fIf\fR\d1\u/\fIf\fR\d2\u= 1.2 to 1.5
.LP
and with a cadence (frequency sequence) as follows:
.LP
	 \fIf\fR\d1\uon 200 ms, silence 200 ms, \fIf\fR\d2\uon 200 ms, silence 
2 |  (one 
cycle is therefore 2.6 | ).
.sp 2P
.LP
9.3
	\fIDuration and level\fR 
.sp 1P
.RT
.PP
9.3.1
A principal purpose of the payphone recognition tone in
international telephony is to identify a called station as a payphone where 
the possibility exists of attempted fraud on a collect call. For this purpose 
the tone must be produced as soon as a payphone answers a call, it must 
be clearly audible to an operator, and it must cease before it can seriously 
interfere 
with conversation.
.sp 9p
.RT
.PP
When the tone is used on an incoming call to payphone, it should have, 
in addition to those characteristics defined in \(sc\ 9.2, a duration of 
5\ complete cycles (13 | ).
.PP
9.3.2 
If the tone is used to identify payphones which are originating
calls, its duration is not specified.
.sp 9p
.RT
.PP
9.3.3 
The specification in \(sc 9.3.1 applies only to the first five cycles of 
the tone when the payphone is the receiving station. 
.sp 9p
.RT
.PP
For use throughout a call or during conversation, the level and
duration of the tone have to meet two contradictory requirements:
.LP
	\(em
	the public exchange operator should be able to detect and
recognise the tone in the presence of the highest expected
levels of speech;
.LP
	\(em
	the tone should not interfere unduly with normal
conversation.
.PP
Experience of customer reaction to the tone requires that the time during 
which the tone is applied should be as short as possible, subject to 
operational requirements.
Similarly the level of the tone should be as low as possible and
significantly lower than the recommended levels for other tones (e.g.,\ 
\(em20\ dBm at the payphone output). The duration of the tone and the level 
at which it is applied are interdependent factors, the shorter the duration 
the higher the 
level and vice versa. (Further studies on the recommended levels and duration 
will be carried out.) 
.sp 2P
.LP
\fB10\fR 	\fBCall waiting tone\fR 
.sp 1P
.RT
.PP
10.1
The call waiting tone is used to advise a subscriber who is
engaged on a call that another subscriber is attempting to call.
.sp 9p
.RT
.PP
10.2
The tone is intended to be sufficiently alerting to succeed in its purpose 
without interfering with existing conversation. 
.sp 9p
.RT
.PP
10.3
The \fIrecommend\fR specification of the tone is one or more cycles defined 
by a frequency\ \fIf\fR in the range: 
.sp 9p
.RT
.LP
	\fIf\fR  |  400 to 450 Hz
.LP
and with a cadence (frequency sequence) as follows:
.LP
	a)
	\fIf\fR on 300 to 500 ms, silence 8 to 10 s (\fIf\fR = 300 ms is
preferable to the longer tone since the ongoing conversation would be
interrupted for a briefer interval); or
.LP
	b)
	 \fIf\fR on 100 to 200 ms, silence 100 to 200 ms, \fIf\fR on 100 to 200 
ms (the total to be no more than 500\ ms); 8 to 10 |  silence. 
.PP
Other tones may be \fIacceptable\fR .
.PP
10.4
The second and subsequent cycles may be at a lower level than the initial 
one. 
.sp 9p
.RT
.PP
10.5
Where the tone continues for more than one cycle, it should
preferably cease when it is no longer possible to accept the waiting call.
.bp
.sp 9p
.RT
.sp 2P
.LP
\fB11\fR 	\fBCaller waiting tone\fR 
.sp 1P
.RT
.PP
11.1
This tone advises a caller that a called station, though busy, has a call 
waiting service active. 
.sp 9p
.RT
.PP
11.2
It is intended that, if this tone is not correctly interpreted by subscribers, 
it be misinterpreted as the ringing tone. 
.sp 9p
.RT
.PP
11.3
To dissuade a caller from waiting indefinitely, the tone may
cease 30\ seconds
.FS
The specification of this time needs further study.
.FE
after it starts and may be replaced by busy tone, or an Administration may
decide to disconnect the calling station.
.sp 9p
.RT
.PP
11.4
The caller waiting tone consists of a ringing tone followed,
after a silent interval of 0 to 200\ ms, by one of the following:
.sp 9p
.RT
.LP
	a)
	the tone defined in \(sc 10.3 | )
.LP
	b)
	the pair of tones defined in \(sc 10.3 | )
.LP
	c)
	another call waiting tone in use by an Administration,
provided that it can be appended to each sounded part of the ringing
tone.
.PP
11.5
The caller waiting tone, as defined in \(sc 11.4, should be
distinguishably different from the ringing tone when directly compared with
it.
.sp 9p
.RT
.sp 2P
.LP
\fB12\fR 	\fBMachine recognition of tones\fR 
.sp 1P
.RT
.PP
The CCITT appreciates the value of machine recognition of tones for the 
purpose of service observations, maintenance, testing or for the collection 
of statistics where equivalent electrical signals do not exist. However, 
the 
CCITT considered, at Mar del Plata in 1968, that such machine recognition
should not be a substitute for electrical signals. Where machine recognition 
of audible tones is to be introduced, the tone frequencies and cadences 
must be 
within close limits of precision.
.PP
For dial tone, ringing tone, busy and congestion tones a working
frequency tolerance of \(+- | % should be met.
.PP
\fINote\fR \ \(em\ The figure of 1% is taken as a compromise out of several
national specifications which vary between \(+- | .5% and \(+- | .5%. (See also
Supplement No.\ 3.)
.RT
.ce 1000
ANNEX\ A
.ce 0
.ce 1000
(to Recommendation E.180)
.sp 9p
.RT
.ce 0
.ce 1000
\fBDigital generation of tones\fR 
.sp 9p
.RT
.ce 0
.PP
The practice of several Administrations and equipment designers for digital 
generation of tones is known to deviate largely: 
.sp 1P
.RT
.LP
	\(em
	in the frequency chosen within the recommended range;
.LP
	\(em
	in the power level which varies with the national
application;
.LP
	\(em
	in the mechanism of generation of tones and signal
frequencies where, in part, the same equipment is used.
.PP
Therefore, it was found difficult to standardize on a fixed number of samples 
with a coded bit\(hystream, which represents one frequency with one 
distinct power level.
.bp
.PP
On the other hand there is no necessity for standardizing digital
generated tones in a more stringent way than analogue generated tones for 
the following reasons: 
.RT
.LP
	\(em
	It is to the interest of Administrations that subscribers
should not be confused by hearing different tones for the same
purpose within their national networks. Consequently
the practice already in use for analogue generated tones should
be maintained for reasons associated with the human factor.
.LP
	\(em
	The advantages that can be achieved by standardizing the code
words for the tones in order to allow automatic recognition of
tones by monitoring the bit stream seem to be so small that they
do not justify a stringent restriction on all possible methods
for digital generation of any frequency allocated with any
level.
.LP
	\(em
	For a long period of time a mixture of analogue and digital
networks will exist. Thus, machine recognition of tones will
have to be performed also with analogue receivers.
.PP
However, when Administrations have full freedom to make new
decisions
about tones in future networks, especially with respect to an all\(hydigital
network, they may consider a preferred solution for the digital generation 
of dial tone, busy tone, congestion tone and ringing tone having a uniform 
frequency of 425\ Hz, as recommended by CCITT.
.ce 1000
ANNEX\ B
.ce 0
.ce 1000
(to Recommendation E.180)
.sp 9p
.RT
.ce 0
.ce 1000
\fBExamples for\fR 
\fBlimitation of spurious components of the dial\fR 
\fBtone\fR 
.sp 9p
.RT
.ce 0
.ce 1000
\fBwith respect to interference with the frequencies\fR 
\fBrecommended\fR 
.ce 0
.ce 1000
\fBfor\fR 
\fBpushbutton telephone sets\fR \fBin\fR \fBRecommendation Q.23\fR 
.ce 0
.LP
B.1
	\fIMethod A\fR  | (used by ATT)
.sp 1P
.RT
.LP
.PP
The total distortion power should be at least 33\ dB less than the dial 
tone power, and the distortion power in any 100\ Hz band above 500\ Hz 
should be at least 40\ dB less than the dial tone power.
.RT
.sp 1P
.LP
B.2
	\fIMethod B\fR  | (used by the Federal Republic of Germany)
.sp 9p
.RT
.PP
In the frequency range from 500 to 2000\ Hz [i.e.,\ the range of
multifrequency pushbutton (MFPB) frequencies] the distortion power in any
100\ Hz band should be at least 40\ dB below the dial tone power. In addition, 
in the frequency range above 2000\ Hz up to 4000\ Hz the total distortion 
power 
should be at least 25\ dB below the dial tone power.
.RT
.sp 2P
.LP
\fBRecommendation\ E.181\fR 
.FS
This Recommendation is also included in the Series Q\ Recommendations under 
the number\ Q.36. 
.FE
.RT
.sp 2P
.sp 1P
.ce 1000
\fBCUSTOMER\ RECOGNITION\ OF\ FOREIGN\ TONES\fR 
.EF '%	Fascicle\ II.2\ \(em\ Rec.\ E.181''
.OF '''Fascicle\ II.2\ \(em\ Rec.\ E.181	%'
.ce 0
.sp 1P
.PP
\fB1\fR 
In order to facilitate recognition of foreign ringing and
busy tones by a subscriber dialling an automatic international call,
the information given to subscribers should:
.sp 1P
.RT
.LP
	1)
	emphasize that a slow repetition rate of the tone
means \*Qringing\*U whereas a rapid repetition rate means \*Qbusy\*U;
.LP
	2)
	indicate that in some countries the 
ringing tone
may be heard as a sequence of two short tones, pause, two more short
tones, pause, and so on.
.PP
In addition, it may be useful for the purpose of educating
subscribers:
.LP
	\(em
	 to provide auditory samples of such tones by tape recording or other 
means, or 
.LP
	\(em
	to include detailed descriptions of tones in
directories.
.bp
.PP
\fB2\fR 
Modern international signalling systems are capable of
exchanging signals corresponding to indications normally given to subscribers 
by means of audible tones (busy, congestion, ringing,\ etc.). Administrations 
are encouraged to arrange their networks so that these information signals 
can be sent between countries in order that they can be recognized and 
converted 
into tones or announcements as near to the calling subscriber as practical.
This procedure could significantly reduce the language problems arising from
the growing use of 
recorded announcements
.
.sp 9p
.RT
.LP
.PP
\fINote\fR \ \(em\ This Recommendation is complementary to
Recommendation\ E.180 on the standardization of tones in the international
telephone network. Whilst standardization is of primary importance, telephone 
users need information to assist them in recognizing foreign tones until 
such time as standardization is complete. 
.PP
This is the purpose of \(sc\ 1 of the present Recommendation which, as
extensive 
human factor
experiments show, should greatly reduce
subscriber confusion.
.PP
The measure mentioned in \(sc\ 2 does not eliminate the need for tone
standardization as well, but can reduce customer difficulties in cases where
standardization may be impractical for a long period but sophisticated
exchanges arrangements are available.
.RT
.sp 2P
.LP
\fBRecommendation\ E.182\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fBAPPLICATION\ OF\ \fR \fBTONES\ AND\ RECORDED\ ANNOUNCEMENTS\fR  |
\fBIN\ TELEPHONE\ SERVICES\fR 
.EF '%	Fascicle\ II.2\ \(em\ Rec.\ E.182''
.OF '''Fascicle\ II.2\ \(em\ Rec.\ E.182	%'
.ce 0
.sp 1P
.LP
	\fBIntroduction\fR 
.sp 1P
.RT
.PP
\fB1\fR 
This Recommendation gives the responses that telephone networks
should provide to subscribers in the operation of both basic and supplementary 
telephone services. Three levels of response may be given: 
.sp 9p
.RT
.LP
	\(em
	preferred responses based solely upon subscriber
requirements;
.LP
	\(em
	accepted responses to be used where technical or economic
reasons inhibit the use of preferred responses;
.LP
	\(em
	exceptional responses to be used where severe technical or
economic constraints prevent the use of preferred or accepted
responses.
.LP
.PP
\fB2\fR It has not been possible in some cases to state a universally
applicable preference between 
recorded announcements
and tones. The
factors influencing such a choice vary widely between Administrations in 
their relative importance. Some features which make recorded announcements 
attractive are: 
.sp 9p
.RT
.LP
	\(em
	 They can reduce the level of calls to operators thus saving considerable 
expense. 
.LP
	\(em
	From a 
human factors
point of view the use of an
excessive number of different tones can be confusing to the user. Recorded
announcements give an opportunity to present a far greater
spectrum of information.
.LP
	\(em
	They can impart more detailed and specific information than   tones.
.LP
	\(em
	 They can have less chance of being misunderstood than tones in situations 
encountered infrequently. 
.PP
Nevertheless recorded announcements have certain drawbacks
also:
.LP
	\(em
	They require more time to convey simple information than a
tone indication would.
.LP
	\(em
	They are meaningless to people who do not understand the
language used. This fact may make their application in
multilingual countries impractical.
.LP
	\(em
	Technical and economic constraints might inhibit their use in some networks.
.LP
	\(em
	Subscribers might not always listen long enough to
distinguish between different announcements.
.bp
.PP
\fB3\fR In this Recommendation, where no preference is stated between
alternative responses, individual Administrations should evaluate the
situation in their own networks taking the above factors into account.
Additional CCITT\ studies will be undertaken to better evaluate the relative
merits of tones and recorded announcements.
.sp 9p
.RT
.PP
\fB4\fR A list of tones and announcements used as indications to telephone 
subscribers is given in Annex\ A. 
.sp 9p
.RT
.sp 2P
.LP
	The\ CCITT,
.sp 1P
.RT
.sp 1P
.LP
\fIconsidering\fR 
.sp 9p
.RT
.PP
(a)
that subscribers set up telephone calls and control
supplementary telephone services
by means of an interchange of
information between the subscriber and the telephone system;
.LP
.PP
(b) 
that information sent by the subscriber to the exchange is standardized 
in several CCITT\ Recommendations, e.g.,\ Recommendation\ E.163 for country 
codes; 
.PP
(c)
that information from the telephone system to the
subscriber can be sent in the form of tones or recorded announcements;
.PP
(d)
that the technical characteristics of the dial tone, the
ringing tone, the busy tone, the congestion tone, the special information 
tone and the warning tone are specified in Recommendation\ E.180 and that 
the 
specification of other tones is studied by the\ CCITT;
.PP
(e) 
that a certain tone or recorded announcement should
unambiguously indicate the desired subscriber action without requiring
subscriber knowledge of the operation of the telephone system;
.PP
(f
) 
that a standardized application of tones and recorded announcements will 
improve subscriber performance and will lead to a more 
efficient use of the telephone network;
.PP
(g) 
that for normal telephone calls and supplementary telephone services an 
identical application of tones and recorded announcements is 
desirable;
.LP
.PP
(h) 
that it is easy to implement standardization of the
application of tones and recorded announcements for new supplementary telephone 
services, but this is more difficult for existing telephone systems and 
should be regarded as a long\(hyterm objective; 
.PP
(i) 
that to avoid abuse of the 
transfer charge service
it is desirable that an operator should be advised when connecting calls to a
payphone
;
.PP
(
j) 
that only tones and announcements are covered in this Recommendation although 
it can be seen that in some cases a visual indication may be an alternative; 
.sp 1P
.LP
\fIrecommends\fR 
.sp 9p
.RT
.PP
(1) 
that this Recommendation shall apply to all telephone
services and telephone networks. PABXs should, with certain indicated
exceptions, use the same tones as the network in the country in which it is
located;
.PP
(2) 
that all tones and recorded announcements should be given as soon as the 
information received by the telephone network is sufficient to 
decide which tone or recorded announcement applies, unless there is an
established subscriber need for the indication to be given later;
.LP
.PP
(3)
that when a subscriber should wait for a network reaction, no tones or 
announcement should be given. This condition applies during, 
e.g.,\ dial\(hytone delay and post\(hydialling delay. Exceptionally when a
post\(hydialling delay on an outgoing international automatic call occurs 
that is likely to cause a subscriber to abandon the call, an appropriate 
announcement or a 
\fIcomfort\fR \fItone\fR may be used if it has been shown to reduce
premature abandonment;
.PP
(4)
that when a subscriber should start dialling, a 
\fIdial\fR \fItone\fR should be given. At PABXs this tone may be different 
from that at 
the public exchange and in this case the tone is named 
\fIPABX internal dial\fR \fItone\fR ;
.PP
(5) 
that when a subscriber should start dialling and a special condition applies 
to his line, a 
\fIspecial dial tone\fR may be given. This condition applies, for example, 
during activated diversion of calls to another number; 
.bp
.PP
(6) 
that, except for PABXs and supplementary services, a second dial tone should 
not be used and a second application of dial tone should also be avoided; 
.PP
(7)
that when a subscriber should wait until the called party
answers and no special condition applies to the line, a 
\fIringing tone\fR should be given;
.PP
(8)
that when the called number is busy and no special condition applies to 
the called line, a 
\fIbusy tone\fR should be given to the
calling subscriber;
.PP
(9) 
that when a special condition of either \*Q
call
waiting
\*U or \*Q
call diversion
\*U applies to a called line, the calling subscriber may be informed about 
the special condition. The responses should 
therefore be either a 
\fIspecific recorded announcement\fR or \fIcaller\fR 
\fIwaiting tone\fR or \fIringing tone\fR . In PABXs a \fIspecial ringing 
tone\fR may be 
used for the \*Qcall waiting\*U service.
.PP
In the case of \*Qcall diversion\*U, if an announcement is given, it is 
necessary to give the announcement before the call is diverted. This especially 
applies if additional call charges have to be paid by the calling party. 
.LP
.PP
(10)
that a subscriber should be informed when the network has
accepted a control order for a supplementary service, e.g.,\ activation,
deactivation, registration, erasure. The responses to be given should be 
either a \fIspecific recorded announcement\fR , e.g.,\ \*Qalarm call booked 
for\ 7.18\*U, a 
\fIgeneral positive recorded announcement\fR , e.g.\ \*Qorder executed\*U or a
\fIpositive indication tone\fR ;
.PP
(11)
that a subscriber \(em after having applied a valid
\fIinterrogation order\fR for a supplementary service\ \(em should be informed 
by the network whether the service is activated or not (status check) or, 
if the 
information dialled is identical to the stored information (data check) or,
specifically what information is stored (data request).
.PP
If a status check or data check applies, the responses to be given should be:
.LP
	\(em
	either a \fIpositive\fR or \fInegative general recorded\fR 
\fIannouncement\fR e.g.,\ \*Qservice (not) active\*U or \*Qinformation 
dialled (not) identical to 
information stored\*U,
.LP
	\(em
	or an appropriate \fIpositive indication tone\fR ,
.LP
	\(em
	or an appropriate 
\fInegative indication tone\fR .
.PP
If a data request applies, the response should be a \fIspecific\fR 
\fIrecorded announcement\fR e.g.\ \*Qalarm call booked for\ 7.18, 9.30 
and\ 12.35\*U 
or \*Qno alarm call booked\*U.
.PP
(12)
that a busy subscriber, having the service \*Qcall waiting\*U
activated, should be informed that an incoming call is waiting. The response 
is 
\fIcall waiting tone\fR ;
.PP
(13)
that when the called number cannot be reached or a control order for activation, 
registration, deactivation, interrogation, or erasure for a supplementary 
service cannot be executed by the network in one attempt, due to \*Qshort\(hyterm 
system nonavailability\*U but a repeated attempt within a short 
time may be successful, a 
\fIcongestion tone\fR should be given. This
condition applies, for example, if short\(hyterm congestion of switching
equipment, circuits or memory storage capacity occurs;
.LP
.PP
(14)
that when the called number cannot be reached or a control order for a 
supplementary service cannot be executed in one attempt due to 
\*Qrecognized long\(hyterm nonavailability\*U and a repeated attempt would 
have no or small probability of success for a longer period of time (e.g.,\ 
a few hours), the preferred response is a \fIspecific recorded announcement\fR 
, e.g.,\ \*Qthe called number is not obtainable because of a network fault, 
please call again after 
(1) hour\*U. Alternatively, a \fIgeneral recorded announcement\fR or 
\fIspecial\fR \fIinformation tone\fR may be used.
.PP
This condition applies when:
.LP
	\(em
	a number is out of order for technical reasons;
.LP
	\(em
	where switching equipment or circuits or memory storage
capacity will not be available for at least a few hours.
.PP
(15)
that when the called number cannot be reached in one attempt because of 
an unresolved condition of the called number due to administrative reasons, 
the preferred response is a \fIspecific recorded announcement\fR 
e.g.,\ \*Qthe
number has been changed, the new number is\ 12345\*U. Alternatively, \fIa 
general\fR \fIrecorded announcement\fR or \fIspecial information tone\fR 
may be used. 
.PP
This condition applies when:
.LP
	\(em
	a number is out of order for administrative reasons;
.LP
	\(em
	a number is not yet connected;
.LP
	\(em
	a number has changed.
.bp
.LP
.PP
(16)
that when the information dialled by the subscriber, for
set\(hyup of an ordinary telephone call or to order a supplementary service, is
not valid or cannot be accepted by the network from that particular line and
the subscriber should check his information and/or his instructions before
making a new attempt:
.LP
	\(em
	 the preferred response is a \fIspecific recorded announcement\fR , e.g.,\ 
\*QIn international dialling to this country the trunk 
prefix\ 0 should be deleted\*U;
.LP
	\(em
	the accepted response is a general negative announcement,
e.g.,\ \*QYou have dialled incorrect information, please consult
your instructions\*U. For PABXs a \fInegative indication tone\fR may be used;
.LP
	\(em
	the exceptional response is a special information tone.
.PP
This condition applies when the number dialled:
.LP
	\(em
	is non\(hyexisting,
.LP
	\(em
	is barred for calls from a particular line,
.LP
	\(em
	contains an incorrect prefix,
.LP
	\(em
	is a control order for a service which is not provided to the particular line.
.LP
.PP
(17) 
that when it is desirable to inform the subscriber to
continue dialling during the ordering of a supplementary service in the
conversational mode, the response to be given should be either a \fIspecific\fR 
\fIrecorded announcement\fR followed by the appropriate dial tone, or a
\fIsecond dial tone\fR ;
.PP
(18)
that an indication should be given when a payphone user is required to 
make a payment during a call. The response to be given should be 
either a \fIspecific recorded announcement\fR or a 
\fIpay tone\fR ;
.PP
(19) 
that an indication should be given to a public network
operator when handling a call from or to a payphone, and that where a tone 
is used: 
.LP
	\(em
	the preferred response is 
\fIpayphone recognition\fR 
\fItone\fR .
.PP
(20) 
that when a subscriber is asked to speak so as to be
recorded by a recording machine, a tone should be given to inform him when 
to begin to speak; the response to be used is the 
\fIrecord tone\fR ;
.PP
(21) 
that when the privacy of a conversation on a call cannot be ensured, e.g.,\ 
because of the intrusion of an operator, the preferred response is the 
\fIintrusion tone\fR given to both subscribers;
.PP
(22) 
that when the privacy of a conversation on a call cannot be ensured, e.g.,\ 
because of the presence of a recording machine, the preferred 
response is the 
\fIwarning tone\fR ;
.PP
(23) 
that all the above\(hymentioned tones should be
different.
.ce 1000
ANNEX\ A
.ce 0
.ce 1000
(to Recommendation E.182)
.sp 9p
.RT
.ce 0
.ce 1000
\fBList of\fR 
\fBtones and announcements used as indications to\fR \fBtelephone subscribers\fR 
.sp 9p
.RT
.ce 0
.PP
\fINote\fR \ \(em\ This annex is provided to explain the terms in
Recommendation\ E.182 and some related terms. It is not a definitive list and
additional refinement will be undertaken as part of future studies.
.sp 1P
.RT
.sp 2P
.LP
A.1
	\fIBasic terms\fR 
.sp 1P
.RT
.sp 1P
.LP
A.1.1
	\fBaudible indication\fR 
.sp 9p
.RT
.LP
	\fIF:\ indication audible\fR 
.LP
	\fIS:\ indicaci\*'on audible\fR 
.PP
An audible indication is understood to be a sound composed of
frequencies within the range\ 300\(hy3400\ Hz which is used to inform the user
about the state of a telephone call or supplementary service.
.bp
.RT
.LP
.sp 1P
.LP
A.1.2
	\fBtone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e\fR 
.LP
	\fIS:\ tono\fR 
.PP
A tone is an audible indication comprising a small number
of discrete frequencies, but excluding speech.
.RT
.sp 1P
.LP
A.1.3
	\fBrecorded announcement\fR 
.sp 9p
.RT
.LP
	\fIF:\ annonce enregistr\*'ee\fR 
.LP
	\fIS:\ anuncio grabado\fR 
.PP
An audible indication in the form of speech.
.RT
.sp 1P
.LP
A.1.4
	\fBcall information\fR 
.sp 9p
.RT
.LP
	\fIF:\ information d'appel\fR 
.LP
	\fIS:\ informaci\*'on de llamada\fR 
.PP
Call information includes normal address information, control
codes for supplementary services, and other information dialled or keyed 
by the subscriber. 
.RT
.sp 2P
.LP
A.2
	\fITones\fR 
.sp 1P
.RT
.sp 1P
.LP
A.2.1
	\fBdial tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e de num\*'erotation\fR 
.LP
	\fIS:\ tono de invitaci\*'on a marcar\fR 
.PP
A tone advising that the exchange is ready to receive call
information and inviting the user to start sending call information.
.RT
.sp 1P
.LP
A.2.2
	\fBPABX internal dial tone\fR 
.sp 9p
.RT
.LP
	 \fIF:\fR \fItonalit\*'e interne de num\*'erotation des commutateurs priv\*'es\fR 
.LP
	\fIS:\fR 	\fItono de invitaci\*'on a marcar interno de centralitas\fR 
\fIprivadas autom\*'aticas conectadas a la red p\*'ublica\fR (tono de marcar 
interno de centralita privada autom\*'atica, CPA) 
.PP
A tone advising that the PABX is ready to receive call information and 
inviting the user to start sending call information. 
.RT
.sp 1P
.LP
A.2.3
	\fBspecial dial tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e sp\*'eciale de num\*'erotation\fR 
.LP
	\fIS:\ tono especial de invitaci\*'on a marcar\fR 
.PP
A tone advising that the exchange is ready to receive call information 
and inviting the user to start sending call information, at the same time 
reminding the user that special conditions apply to the termination from 
which the call is being made. 
.RT
.LP
.sp 1P
.LP
A.2.4
	\fBsecond dial tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ seconde tonalit\*'e de num\*'erotation\fR 
.LP
	\fIS:\ segundo tono de invitaci\*'on a marcar\fR 
.PP
A tone advising the caller that the network has accepted the call information 
already sent and asking the caller to provide more 
information.
.RT
.sp 1P
.LP
A.2.5
	\fBringing tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e de retour d'appel\fR 
.LP
	\fIS:\ tono de llamada\fR 
.PP
A tone advising the caller that a connection has been made and that a calling 
signal is being applied to a telephone number or service 
point.
.bp
.RT
.sp 1P
.LP
A.2.6
	\fBbusy tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e d'occupation\fR 
.LP
	\fIS:\ tono de ocupado\fR 
.PP
A tone advising the caller that the telephone number is
busy.
.RT
.LP
.sp 1P
.LP
A.2.7
	\fBcongestion tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e d'encombrement\fR 
.LP
	\fIS:\ tono de congesti\*'on\fR 
.PP
A tone advising the caller that the groups of lines or switching equipment 
necessary for the setting\(hyup of the required call or for the use of 
a specific service are temporarily engaged. 
.RT
.sp 1P
.LP
A.2.8
	\fBspecial information tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e sp\*'eciale d'information\fR 
.LP
	\fIS:\ tono especial de informaci\*'on\fR 
.PP
A tone advising the caller that the called number cannot be
reached for reasons other than \*Qsubscriber busy\*U or \*Qcongestion\*U.
.PP
The tone may also be used in conjunction with recorded announcements to 
signify that what the caller is about to hear is a recording. It should 
always be used to precede all call failure announcements.
.RT
.LP
.sp 1P
.LP
A.2.9
	\fBwarning tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e d'avertissement\fR 
.LP
	\fIS:\ tono de aviso\fR 
.PP
A tone warning participants in a call that privacy of a
conversation cannot be ensured where a recording machine is being used.
.RT
.sp 1P
.LP
A.2.10
	\fBintrusion tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e d'intrusion\fR 
.LP
	\fIS:\ tono de intervenci\*'on\fR 
.PP
A tone advising participants during a call that the
privacy of the conversation has been breached, e.g.\ by the intervention 
of an operator. 
.RT
.sp 1P
.LP
A.2.11
	\fBcall waiting tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e d'appel en attente\fR 
.LP
	\fIS:\ tono de indicaci\*'on de llamada en espera\fR 
.PP
A tone advising the user of the call waiting supplementary service
who is engaged on a call that someone is attempting to call his number.
.RT
.sp 1P
.LP
A.2.12
	\fBpay tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e de paiement\fR 
.LP
	\fIS:\ tono de pago\fR 
.PP
A tone advising users of a payphone that a payment is required.
.RT
.sp 1P
.LP
A.2.13
	\fBpayphone recognition tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e d'identification de publiphone\fR 
.LP
	\fIS:\ tono de identificaci\*'on de tel\*'efono de previo pago\fR 
.PP
A tone advising a public exchange operator that the termination to or from 
which connection is sought is identified as a payphone. 
.bp
.RT
.sp 1P
.LP
A.2.14
	\fBcomfort tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e de file d'attente\fR 
.LP
	\fIS:\ tono de paciencia\fR 
.PP
A tone advising that the call is being processed and that the
caller should wait.
.RT
.LP
.sp 1P
.LP
A.2.15
	\fBtone on hold\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e de garde\fR 
.LP
	\fIS:\ tono de retenci\*'on\fR 
.PP
A tone used to reassure a calling subscriber who has been placed on \*Qhold\*U 
by a subscriber with PBX or other facilities. 
.RT
.sp 1P
.LP
A.2.16
	\fBrecord tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e d'enregistrement\fR 
.LP
	\fIS:\ tono de grabaci\*'on\fR 
.PP
A tone generated by automatic answering equipment to inform the
calling subscriber when to begin a message which will be recorded.
.RT
.sp 1P
.LP
A.2.17
	\fBcaller waiting tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e de demandeur en attente\fR 
.LP
	\fIS:\ tono de indicaci\*'on de llamada en espera para el llamande\fR 
.PP
A tone advising a caller that a called station, though busy, has a call 
waiting service active. 
.RT
.sp 1P
.LP
A.2.18
	\fBpositive indication tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e d'indication positive\fR 
.LP
	\fIS:\ tono de indicaci\*'on positivo\fR 
.PP
A tone telling a subscriber controlling a supplementary service
that the control procedure has been successfully completed and accepted.
.RT
.sp 1P
.LP
A.2.19
	\fBnegative indication tone\fR 
.sp 9p
.RT
.LP
	\fIF:\ tonalit\*'e d'indication negative\fR 
.LP
	\fIS:\ tono de indicaci\*'on negativo\fR 
.PP
A tone advising a subscriber that the request for service cannot   be accepted.
.RT
.LP
.sp 2P
.LP
A.3
	\fIRecorded announcements\fR 
.sp 1P
.RT
.sp 1P
.LP
A.3.1
	\fBgeneral recorded announcement\fR 
.sp 9p
.RT
.LP
	\fIF:\ annonce enregistr\*'ee g\*'en\*'erale\fR 
.LP
	\fIS:\ anuncio grabado general\fR 
.PP
A recorded announcement giving general information about a call
attempt or control order.
.bp
.RT
.sp 1P
.LP
A.3.2
	\fBgeneral positive recorded announcement\fR 
.sp 9p
.RT
.LP
	\fIF:\ annonce enregistr\*'ee g\*'en\*'erale positive\fR 
.LP
	\fIS:\ anuncio grabado general positivo\fR 
.PP
A recorded announcement given to the user of a supplementary
service to advise that the request has been accepted.
.RT
.LP
	\fIExample\fR 
.LP
	\*QYour order has been executed.\*U
.sp 1P
.LP
A.3.3
	\fBgeneral negative recorded announcement\fR 
.sp 9p
.RT
.LP
	\fIF:\ annonce enregistr\*'ee g\*'en\*'erale negative\fR 
.LP
	\fIS:\ anuncio grabado general negativo\fR 
.PP
A recorded announcement given to the user of a supplementary
service to advise that the request cannot be executed or that the call 
cannot be completed. 
.RT
.LP
	\fIExamples\fR 
.LP
	\*QYour order cannot be executed.\*U
.LP
\*QYour call cannot be completed at this time.\*U
.LP
\*QPlease try again.\*U
.sp 1P
.LP
A.3.4
	\fBspecific recorded announcement\fR 
.sp 9p
.RT
.LP
	\fIF:\ annonce enregistr\*'ee sp\*'ecifique\fR 
.LP
	\fIS:\ anuncio grabado espec\*'ifico\fR 
.PP
A recorded announcement giving specific information about a call attempt 
or control order. 
.RT
.sp 1P
.LP
A.3.5
	\fBspecific positive recorded announcement without supplementary
information\fR 
.sp 9p
.RT
.LP
	\fIF:\fR 	\fIannonce enregistr\*'ee sp\*'ecifique positive sans\fR 
\fIinformation suppl\*'ementaire\fR 
.LP
	 \fIS:\fR \fIanuncio grabado espec\*'ifio positivo sin informaci\*'on\fR 
\fIsuplementaria\fR 
.PP
A recorded announcement indicating to the user that the request
for a particular supplementary service has been accepted.
.RT
.LP
	\fIExample\fR 
.LP
	\*QThe call barring service is now in operation.\*U
.LP
.sp 1P
.LP
A.3.6
	\fBspecific negative recorded announcement without supplementary
information\fR 
.sp 9p
.RT
.LP
	\fIF:\fR 	\fIannonce enregistr\*'ee sp\*'ecifique n\*'egative sans\fR 
\fIinformation suppl\*'ementaire\fR 
.LP
	 \fIS:\fR \fIanuncio grabado espec\*'ifico negativo sin informaci\*'on\fR 
\fIsuplementaria\fR 
.PP
A recorded announcement indicating to the user that the request for a particular 
supplementary service cannot be executed or that the call cannot be completed. 
.RT
.LP
	\fIExamples\fR 
.LP
	\*QYour order for call transfer cannot be executed.\*U
.LP
	\*QThe called number is not obtainable because of a network
fault.\*U
.sp 1P
.LP
A.3.7
	\fBspecific positive recorded announcement with supplementary
information\fR 
.sp 9p
.RT
.LP
	\fIF:\fR 	\fIannonce enregistr\*'ee sp\*'ecifique positive avec\fR 
\fIinformation suppl\*'ementaire\fR 
.LP
	 \fIS:\fR \fIanuncio grabado espec\*'ifico positivo con informaci\*'on\fR 
\fIsuplementaria\fR 
.PP
A recorded announcement complete with the supplementary
information received indicating to the user that a certain condition is 
being established. 
.RT
.LP
	\fIExample\fR 
.LP
	\*QAn alarm call is booked for\ 06.30.\*U
.bp
.sp 2P
.LP
\fBRecommendation\ E.183\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fBGUIDING\ PRINCIPLES\ FOR\ \fR \fBTELEPHONE\ ANNOUNCEMENTS\fR 
.EF '%	Fascicle\ II.2\ \(em\ Rec.\ E.183''
.OF '''Fascicle\ II.2\ \(em\ Rec.\ E.183	%'
.ce 0
.sp 1P
.LP
\fB1\fR 	\fBIntroduction\fR 
.sp 1P
.RT
.PP
Recorded announcements are of great value in the setting up of a
call or supplementary service.
.PP
Administrations will need to use an announcement system which makes
the announcements in real time and which permits the inclusion of specific
information relating to a particular call or situation. This can be done by
storing words or parts of words which can be appropriately assembled to make
up the required announcements. These are called 
\*Qconcatenated\(hyword\*U
announcements
.
.PP
Another approach is to use truly synthetic speech (synthesis\(hyby\(hyrule), 
generated in real time, to produce announcements as required. This avoids 
the need to store representations of utterances by a natural speaker, and 
has the advantage of total flexibility in the announcement that can be 
produced. 
.RT
.sp 2P
.LP
\fB2\fR 	\fBContent of announcements\fR 
.sp 1P
.RT
.PP
2.1
Announcements should not commence with a significant word.
.sp 9p
.RT
.PP
2.2
Ideally only one piece of information should be conveyed in an
instructional announcement
, but for practical purposes a maximum of
three is recommended.
.PP
2.3
Repetition of important items of information is advisable.
Announcements such as acknowledgement messages and error messages should be
produced twice. However, 
guidance announcements
which ask for input
from the user should normally be produced only once.
.PP
2.4
Announcements should be phrased in a polite manner.
.PP
2.5
Announcements should be concise. This requirement is especially
important for guidance announcements.
.PP
2.6
In many languages, simple affirmative sentences are most easily
understood and should be used where possible, rather than negative and 
passive sentences. The use of negatives can sometimes be helpful, however, 
when 
emphasizing a point (e.g.,\ as in \*QDo not\ . |  | \*U).
.PP
2.7
If applicable, the order in which procedural guidance is presented should 
correspond to the order in which actions are required to be executed 
(e.g.,\ \*QPlease press the ##\ button and then replace the receiver\*U, 
rather than \*QBefore replacing the receiver, please press the ##\ button). 
.PP
2.8
If an action and its consequence are described, the consequence
should be stated first, then the action (e.g.,\ \*QTo receive this message, 
please press the ##\ button\*U, rather than \*QPlease press the ##\ button 
to receive the 
message\*U).
.PP
2.9
Where necessary, announcements should be given in more than one
language.
.PP
2.10
Jargon should be avoided.
.LP
.PP
2.11
When several words or phrases could be used to convey the same
idea (e.g.,\ handset/receiver, hang\(hyup/clear\(hydown,\ etc.), one should 
be selected and used throughout. 
.sp 2P
.LP
\fB3\fR 	\fBTiming of announcements\fR 
.sp 1P
.RT
.PP
3.1
Announcements should start at the beginning for each customer
receiving them.
.sp 9p
.RT
.PP
3.2
The speech rate should not exceed normal conversation speed. For example, 
normal speech rate for the English language is 150\ to 200\ words or 
300\ to 500\ syllables per minute.
.PP
3.3
Attention should be given to the distribution of pauses within
announcements, in order to allow listeners to digest items of information.
.PP
3.4
If an announcement is repeated once, the pause between the
original announcement and its repetition should be about 2\ seconds. Where
announcements are required to be repeated more than once the pause between
announcements may be extended (for instance 5\ to 10\ seconds).
.bp
.LP
.PP
3.5
The use of pauses within telephone numbers or items of information that 
have to be remembered or written down is recommended (for instance 500 
to 1000\ msec within a digit sequence). 
.PP
Telephone numbers should be grouped with groups of two to four
digits according to the custom.
.sp 2P
.LP
\fB4\fR 	\fBSpeech quality\fR 
.sp 1P
.RT
.PP
4.1
Announcements should not sound as if they have finished when they have 
not, nor should they sound as if they continue when they have finished. 
.sp 9p
.RT
.PP
4.2
The speech quality of announcements should be assessed by
listeners' subjective judgements from the user's end. The quality should 
refer to the whole system, including effects of transmission. A measuring 
method that can be used is the listening opinion test described in Volume\ 
V, Supplement\ 2. 
.sp 2P
.LP
\fB5\fR 	\fBTones after announcements\fR 
.sp 1P
.RT
.PP
5.1
After guidance announcements which ask for input from the user an indication 
to proceed should be given (in some cases dial tone will be 
appropriate).
.sp 9p
.RT
.LP
.PP
5.2
When the user is required to replace the receiver following an
announcement, congestion tone may be used.
.sp 2P
.LP
\fB6\fR 	\fBConcatenated\(hyword announcements\fR 
.sp 1P
.RT
.PP
Problems which are peculiar to concatenated\(hyword speech are
described in the following paragraphs:
.RT
.sp 1P
.LP
6.1
	\fIFluency problems\fR 
.sp 9p
.RT
.PP
The 
fluency of an announcement
is influenced by the
duration of the stored speech segment (for instance 1/16\ second), and by the
location of words within a segment or segments. Fluency may also be influenced 
by the insertion of additional silent segments between segments of speech. 
An iterative procedure of vocabulary editing and listening to the results 
until it is judged acceptable is recommended. Human factor tests need to 
be included in the iterative procedure. Experiments should be held with 
the typical 
users.
.RT
.sp 1P
.LP
6.2
	\fIIntonation problems\fR 
.sp 9p
.RT
.PP
Problems arise because speech is required to sound natural.
Ideally only one version of each word would be assembled from segments 
held in store, as this would be the easiest and cheapest method of providing 
a range of announcements. However, the 
intonation pattern of a word
may need to
vary depending on the position of the word within a sentence.
.PP
For example:
.RT
.LP
	a)
	\*QAll calls to XXXX are being \fIdiverted\fR \*U.
.LP
	The stress on the word \*Qdiverted\*U falls towards the end of the
word.
.LP
	b)
	\*QYour call to Dr. Smith is being \*Qdiverted\*U to Dr. Jones\*U.
.LP
	The pitch of the word \*Qdiverted\*U is neutral.
.sp 1P
.LP
6.3
	\fIPresentation of numerical information\fR 
.sp 9p
.RT
.PP
Numerical information, and in particular telephone numbers, can be more 
easily remembered if spoken in a familiar manner. This may necessitate 
different rules for different countries, and may be influenced by such 
things as 
numbering plan
and custom. (For example, a 3\ or 4\ digit area code
separated by a pause from a 5 or 6 digit local number. The number 7230 
could be spoken as \*Qseven, two, three, oh\*U or \*Qseventy\(hytwo, thirty\*U 
or \*Qseven, two, 
three, zero\*U).
.PP
In many languages, three 
intonation patterns
are required for telephone numbers, a neutral pattern for the body of the 
number, a continuant pattern for the end of an intermediate block (rising 
pitch), and a terminator for the end of the number (falling pitch). Number 
strings are more easily 
remembered if spoken with a rhythm based on the perceptual centres of
utterances (e.g.,\ digits), rather than with one based on the start of the
utterance period.
.PP
The final determinant of what is required in a particular case depends 
upon the iterative procedure of listening, editing and judging previously 
mentioned.
.bp
.RT
.sp 1P
.LP
6.4
	\fIUpdate problems\fR 
.sp 9p
.RT
.PP
Problems may arise when an announcement has to be changed such
that a word or words have to be either rerecorded or recorded for the first
time. There may be difficulty in obtaining the original speaker, and even 
if the original speaker is available the voice may differ from the original 
recording, either temporarily (e.g.,\ by a head cold) or permanently
(e.g.,\ through ageing).  This can mean that the entire vocabulary has to be
recorded again, or alternatively an announcement of degraded quality may be
accepted as an expedient solution. Wherever possible, problems of this sort
should be anticipated, and recordings made of a larger vocabulary than 
is to be used immediately. 
.RT
.LP
.sp 2P
.LP
\fB7\fR 	\fBTones and announcements for use in telephone services\fR 
.sp 1P
.RT
.PP
The problems associated with \*Qconcatenated\(hyword\*U systems outlined 
above are avoided by the use of truly synthetic speech generated by rule. 
These rules translate a specification of what utterance is to be generated 
into 
acoustic output. If appropriate rules are found, this method can potentially
generate high quality speech, and such features as speed of delivery, duration 
of pauses, and stress and pitch changes can be readily specified. One approach 
to the development of such systems starts with the use of natural speech 
analysis as the source for generating rule parameters, and leads on to the
derivation of general rules to convert any message into speech output.
.PP
Rule\(hygenerated synthetic speech
is currently on the threshold of full functional equivalence with that 
produced by waveform storage methods, such as word concatenation. However, 
even highly intelligible synthetic speech sounds unnatural and it may not 
be as acceptable to users as 
\*Qconcatenated\(hywords\*U announcements, at least in the immediate future.
.RT
.LP
.sp 2P
.LP
\fB8\fR 	\fBPreferred listening levels for announcements\fR 
.sp 1P
.RT
.PP
The preferred listening level is \(em10\ dBPa \(+- | \ dB measured at the
customer's ear.
.RT
.sp 2P
.LP
\fBRecommendation\ E.184\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fBINDICATIONS\ TO\ USERS\ OF\ ISDN\ TERMINALS\fR 
.EF '%	Fascicle\ II.2\ \(em\ Rec.\ E.184''
.OF '''Fascicle\ II.2\ \(em\ Rec.\ E.184	%'
.ce 0
.sp 1P
.LP
\fB1\fR 	\fBIntroduction\fR 
.sp 1P
.RT
.PP
1.1
Recommendations E.180 to E.184 deal with tones and other
indications to users of the telephone service. This Recommendation covers 
the related but perhaps different requirements of the ISDN. 
.sp 9p
.RT
.PP
1.2
A person's ability to learn, distinguish between, and remember
different tones representing abstract conditions is limited (to about four 
to six tones). Users are frequently confused by unfamiliar tones encountered 
through travel or international communication. Section\ 2 of this Recommendation 
advises against the use of new tones in order to avoid introducing user 
difficulties.
.PP
1.3
Where indications originate from a network (as proposed to a
distant terminal), two situations may exist between the origin of the
indications and the user of an ISDN terminal:
.LP
	a)
	ISDN signalling is used throughout
.LP
	b)
	In\(hyband signalling is used in some parts of the
connection.
.PP
1.4
Considering that information is sent to an ISDN terminal on a
D\(hychannel, and that the terminal may transform it into perceptible form,
choices exist as to
.FS
The desirability of translating various ISDN
indications, the situations governing such choices, and the relationships of
these to terminal capability (particularly display capability), are subjects
for further study.
.FE
the most appropriate way of passing indications on to the user (e.g.,\ 
by means of a display or by tones). 
.bp
.sp 2P
.LP
\fB2\fR 	\fBIndications in an all\(hyISDN communication path\fR 
.sp 1P
.RT
.PP
2.1
It is recommended that no new tone (i.e., tones not in use in the PSTN) 
be generated by an ISDN terminal. 
.sp 9p
.RT
.PP
2.2
Tones are recommended where an auditory method other than \*Qspeech\*U 
or announcements is chosen as the method for a terminal to translate received 
D\(hychannel ISDN information for a user. Such tones should be those used 
in the PSTN in the country where the terminal is situated (Recommendation\ 
E.180). 
.PP
2.3
It is recommended that where a terminal translates ISDN signalling to tones, 
such tones should be used with meanings analogous to their meanings in 
the PSTN. 
.PP
2.4
It is recommended that the use of tones should be restricted to
indicating the functions equivalent to the tones used in the PSTN and listed 
in Recommendation\ E.182, \(sc\ A.2. In some cases, notably dial tone, 
ringing tone, 
and busy
tone, these tones may be the best indicators even when other methods can be
provided by a terminal.
.sp 2P
.LP
\fB3\fR 	\fBIndications when ISDN is interworking with another network\fR 
.sp 1P
.RT
.PP
Given that no tone recognition is likely to be provided by any
network element for translating a tone into an ISDN signal for relaying to a
terminal, it is recommended that any audible indication arising from a 
non\(hyISDN network be passed through an auditory channel to the ISDN terminal. 
.RT
.LP
.rs
.sp 30P
.LP
.bp
.LP
\fBMONTAGE:\ \fR PAGE 210 = PAGE BLANCHE
.sp 1P
.RT
.LP
.bp