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\fBRecommendations Q.310 to Q.331\fR \v'2P'
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\fBSPECIFICATIONS\ OF\ SIGNALLING\ SYSTEM\ R1\fR 
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\fBMONTAGE:\fR PAGE 2 = PAGE BLANCHE
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\s10\fBSIGNALLING\ SYSTEM\ R1\fR \s9\v'3P'
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INTRODUCTION
.EF '%	Fascicle\ VI.4\ \(em\ System\ R1''
.OF '''Fascicle\ VI.4\ \(em\ System\ R1	%'
.ce 0
.sp 1P
.ce 1000
\fBPRINCIPLES\ OF\ SIGNALLING\ SYSTEM\ R1\fR 
.ce 0
.sp 1P
.LP
\fIGeneral\fR 
.sp 1P
.RT
.PP
The development of new exchanges, especially those utilizing
stored programme control
, has introduced new concepts in the division of functions between various 
components of signalling and switching systems. To allow the maximum freedom 
in incorporating new concepts which can contribute to the overall economy 
and efficiency of the system, the requirements as covered in this specification 
are for the combination of equipments necessary to 
.PP
provide a function. For example, the requirements for line signal receiving
equipment as given here may be met by various subdivisions of functions
between signal receiver, trunk relay sets and stored programme control.
.PP
System\ R1 may be applied for automatic and semi\(hyautomatic operation 
of one\(hyway and both\(hyway circuits, within an international region 
(world 
numbering zone). When utilized in an 
integrated world numbering zone
(e.g.\ Zone\ 1) the numbering and routing plans and operating facilities 
of that zone should apply. 
.PP
The system is applicable to all types of circuits (except\ TASI derived 
circuits) 
.FS
Register signalling can be made compatible with TASI by providing a TASI 
locking tone. 
.FE
meeting CCITT transmission standards, including
satellite circuits.
.PP
The signalling equipment used in System\ R1 consists of two
parts:
.RT
.LP
	\fIa)\fR 	line signalling for line or supervisory signals; and
.LP
	\fIb)\fR 	register signalling for address signals.
.LP
.sp 2P
.LP
a)
	\fILine signalling\fR 
.sp 1P
.RT
.sp 1P
.LP
1)
	\fI2600 Hz signalling\fR 
.sp 9p
.RT
.PP
Continuous tone type in\(hyband line\(hysignalling
is used for
the link\(hyby\(hylink transmission of all supervisory signals except the
ring\(hyforward (forward\(hytransfer) signal which is a spurt signal. A single
frequency, 2600\ Hz, is used in each direction of the 4\(hywire transmission 
path, the presence or absence of this frequency indicates a specific signal 
dependent upon when it occurs in the signalling sequence and in certain 
cases upon its 
duration. When the circuit is idle, a low level signalling tone is continuously 
present in both directions. 
.RT
.LP
.sp 3
.bp
.sp 1P
.LP
2)
	\fIPCM signalling\fR 
.sp 9p
.RT
.PP
The 2600\ Hz line signalling described in 1) is not normally applied to 
the speech paths of circuits working on PCM\ systems unless the PCM\ channels 
are connected in cascade with analogue channels to form a circuit. The 
signalling on PCM\ systems in the North American region is channel associated, 
in\(hyslot, providing two signalling channels per speech channel, and utilizing 
bit stealing of the eighth bit of each channel every sixth frame.
.RT
.sp 1P
.LP
b)
	\fIRegister signalling\fR 
.sp 9p
.RT
.PP
See in Fascicle VI.2, Recommendation Q.151, Note to \(sc\ 3.1.1 for an 
explanation of these terms. 
.FE
Link\(hyby\(hylink multifrequency (MF) in\(hyband pulse signalling
is used for the transmission of address information. The signalling frequencies 
are 700\ Hz to 1700\ Hz, in 200\ Hz steps, and combinations of two, and 
two only, determine the signal. The address information is preceded by 
a KP\ signal 
.PP
(start\(hyof\(hypulsing) and terminated by an ST\ signal (end\(hyof\(hypulsing). 
Either \fIen\fR \fIbloc\fR , or \fIen bloc\fR overlap 
, or overlap sending may apply.
This register signalling arrangement is used extensively with other in\(hyband 
and out\(hyband line signalling systems. 
.PP
Compandors may affect signalling, particularly short pulse compound
register signals, due to pulse length distortion and the production of
intermodulation frequencies. By virtue of the link\(hyby\(hylink signalling 
and the adopted duration of register and line signal pulses, System\ R1 
functions 
correctly in the presence of compandors designed in accordance with CCITT
recommendations.
.RT
.LP
.rs
.sp 28P
.LP
.bp
.sp 1P
.ce 1000
\v'3P'
SECTION\ 1
.ce 0
.sp 1P
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\fBDEFINITION\ AND\ FUNCTION\ OF\ SIGNALS\fR 
.ce 0
.sp 1P
.sp 2P
.LP
\fBRecommendation\ Q.310\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB1.\ DEFINITION\ AND\ FUNCTION\ OF\ SIGNALS\fR 
.FS
In this part the
North American designation for line signals is used. The designation of the
signal in System\ No.\ 5 which most nearly corresponds to a particular North
American signal is shown in parentheses. There is not always exact
correspondence in function, e.g.\ the ring\(hyforward signal can only be
effective when a connection has been established through an incoming
operator.
.FE
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.310''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.310	%'
.ce 0
.sp 1P
.sp 2P
.LP
1.1
	\fBconnect (seizing) signal\fR (sent in the forward direction)
.sp 1P
.RT
.PP
This line signal is transmitted at the beginning of a call to
initiate circuit operation at the incoming end of the circuit to busy the
circuit and to seize equipment for switching the call.
.RT
.sp 1P
.LP
1.2
	\fBdelay\(hydialling signal\fR (sent in the backward direction)
.sp 9p
.RT
.PP
This line signal is transmitted by the incoming exchange following the 
recognition of the connect (seizing) signal to verify receipt of the 
connect (seizing) signal and to indicate that the incoming register equipment 
is not yet attached or ready to receive address signals. 
.RT
.sp 1P
.LP
1.3
	\fBstart\(hydialling (proceed\(hyto\(hysend) signal\fR (sent in the backward
direction)
.sp 9p
.RT
.PP
This line signal is sent from the incoming exchange subsequent to the sending 
of a delay\(hydialling signal to indicate that the incoming register equipment 
has been connected and is ready to receive address signals. 
.RT
.LP
.sp 1P
.LP
1.4
	\fBKP (start\(hyof\(hypulsing) signal\fR (sent in the forward direction)
.sp 9p
.RT
.PP
This register signal is sent subsequent to the recognition of a
start\(hydialling signal and is used to prepare the incoming multifrequency
register for the receipt of subsequent interregister signals.
.RT
.sp 1P
.LP
1.5
	\fBaddress signal\fR (sent in the forward direction)
.sp 9p
.RT
.PP
This register signal is sent to indicate one decimal element of
information (digit\ 1,\ 2,\ . |  | ,\ 9 or\ 0) about the called party's 
number. For 
each call a succession of address signals is sent.
.RT
.sp 1P
.LP
1.6
	\fBST (end\(hyof\(hypulsing) signal\fR (sent in the forward direction)
.sp 9p
.RT
.PP
This register signal is sent to indicate that there are no more
address signals to follow. The signal is always sent in semi\(hyautomatic 
as well as automatic working. 
.RT
.LP
.sp 2
.bp
.sp 1P
.LP
Notes on the answer and hang\(hyup (clear\(hyback) signals.\ \(em\ See
corresponding notes in Recommendation\ Q.120, \(sc\ 1.8, Volume\ VI\(hy2 of the
\fIGreen Book\fR .
.FE
1.7
	\fBanswer signal\fR (sent in the backward direction)
,
.FS
See Recommendation Q.27 for the actions to be taken to assure that answer 
signals, both national and international, are transmitted as quickly as 
possible.
.FE
.sp 9p
.RT
.PP
This line signal is sent to the outgoing exchange to indicate that the 
called party has answered. 
.PP
In semi\(hyautomatic working, the signal has a supervisory function.
.PP
In automatic working, it is used:
.RT
.LP
	\(em
	to start metering the charge to the calling subscriber;
.LP
	\(em
	 to start the measurement of call duration for international accounting 
purposes, if this is desired. 
.LP
.sp 1P
.LP
1.8
	\fBhang\(hyup (clear\(hyback) signal\fR (sent in the backward
direction)
.sp 9p
.RT
.PP
This line signal is sent to the outgoing exchange to indicate that the 
called party has cleared. In the semi\(hyautomatic service it performs 
a 
supervisory function.
.PP
In automatic working, arrangements are made to clear the connection, stop 
the charging, and stop the measurement of call duration if within\ 10 to 
120\ seconds
.FS
In word numbering Zone\ 1, 13 to 32\ seconds is used.
.FE
after recognition of the hang\(hyup signal, the calling subscriber has 
not cleared. 
Clearing of the connection should preferably be controlled from the point 
where the charging is carried out. 
.RT
.sp 1P
.LP
1.9
	\fBring\(hyforward (forward\(hytransfer) signal\fR (sent in the forward
direction)
.sp 9p
.RT
.PP
This line signal is initiated by an operator to recall an operator at a 
point further ahead in the connection. 
.RT
.sp 1P
.LP
1.10
	\fBdisconnect (clear\(hyforward) signal\fR (sent in the forward
direction)
.sp 9p
.RT
.LP
.PP
This line signal is sent in the forward direction at the end of a  call when:
.RT
.LP
	\fIa)\fR 	in semi\(hyautomatic working, the operator at the outgoing
exchange withdraws the plug from the jack, or when an equivalent
operation is performed;
.LP
	 \fIb)\fR in automatic working, the calling party hangs up, or when the 
time\(hyout period of\ 10 to 120\ seconds as discussed in \(sc\ 1.8\ above 
occurs.
.sp 1P
.LP
1.11
	\fIDiagrams showing signal sequence\fR 
.sp 9p
.RT
.PP
Typical sequences of signals in semi\(hyautomatic and automatic
working are shown in Annex\ A to these Specifications of Signalling
System\ R1.
.RT
.LP
.rs
.sp 13P
.LP
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.sp 1P
.ce 1000
\v'3P'
SECTION\ 2
.ce 0
.sp 1P
.ce 1000
\fBLINE\ SIGNALLING\fR 
.ce 0
.sp 1P
.sp 2P
.LP
\fBRecommendation\ Q.311\fR 
.RT
.sp 2P
.LP
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.311''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.311	%'
.sp 1P
.ce 1000
\fB2.1\ 2600\ Hz\ LINE\ SIGNALLING\fR 
.ce 0
.sp 1P
.PP
The line\(hysignal coding arrangement is based on the application and removal 
of a 
single frequency tone (2600\ Hz)
as shown in
Table\ 1/Q.311.
.sp 1P
.RT
.LP
.rs
.sp 33P
.ad r
\fBTable [1/Q.311], p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
By taking advantage of the fixed order of occurrence of specific
signals, both tone\(hyon and tone\(hyoff signals are used to indicate more 
than one signal condition. For example, in the backward direction tone\(hyon 
is used to 
indicate start\(hydialling (proceed\(hyto\(hysend), and terminating end 
hang\(hyup 
(clear\(hyback) signals without conflict. The equipment must retain memory 
of the preceding signal states and the direction of signals in order to 
differentiate between tone\(hyon and tone\(hyoff signals. 
.sp 2P
.LP
\fBRecommendation\ Q.312\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB2.2\ \fR \fB2600\ Hz\ LINE\ SIGNAL\ SENDER\fR 
.FS
See also
Recommendation\ Q.112.
.FE
\fB\ (TRANSMITTER)\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.312''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.312	%'
.ce 0
.sp 1P
.sp 2P
.LP
2.2.1
	\fISignal frequency\fR 
.sp 1P
.RT
.PP
2600\ \(+-\ 5\ Hz.
.RT
.sp 1P
.LP
2.2.2
	\fITransmitted signal level of tone\(hyon signals\fR 
.sp 9p
.RT
.PP
\(em8\ \(+-\ 1\ dBm0 for the duration of the signal or for a minimum of
300\ ms (whichever is shorter) and for a maximum of 550\ ms after which 
the level of the signal shall be reduced to \(em20\ \(+-\ 1\ dBm0. 
.RT
.sp 1P
.LP
2.2.3
	\fITransmitted signal durations\fR 
.sp 9p
.RT
.PP
The transmitted signal durations are shown in Table\ 1/Q.311.
.RT
.sp 1P
.LP
2.2.4
	\fISignal frequency leak\fR 
.sp 9p
.RT
.PP
The level of signal frequency leak power transmitted to the line
should not exceed \(em70\ dBm0, during the tone\(hyoff condition.
.RT
.LP
.sp 1P
.LP
2.2.5
	\fIExtraneous frequency components\fR 
.sp 9p
.RT
.PP
The total power of extraneous frequency components accompanying a tone 
signal should be at least 35\ dB below the fundamental signal power. 
.RT
.sp 1P
.LP
2.2.6
	\fITransmitting line split\fR 
.sp 9p
.RT
.PP
The following splitting arrangements are required when transmitting line 
signals to prevent incorrect operation of the receiving equipment due to 
transients caused by the opening or closing of direct current circuits 
in the exchange at the transmitting end: 
.RT
.LP
	\fIa)\fR 	when a tone\(hyon signal is to be transmitted, the speech
path from the exchange shall be split (disconnected), if not
already split, within an interval from 20\ ms before, to
5\ ms
.FS
The 5\ ms may be relaxed to 15\ ms if tone is applied
while tone is being received.
.FE
after tone is applied to
the line, and remain split for a minimum of 350\ ms and a maximum
of 750\ ms;
.LP
	\fIb)\fR 	when a tone\(hyoff signal is to be transmitted, the speech
path from the exchange shall be split (disconnected), if not
already split, within an interval from 20\ ms before to 5\ ms
after tone is removed from the line, and remain split for a
minimum of 75\ ms and a maximum of 160\ ms after the tone is
removed;
.LP
	\fIc)\fR 	when the signalling equipment is receiving and sending
tones simultaneously the split shall be maintained until:
.LP
	i)
	the transmitted tone is terminated, in which case
the split must be removed in the interval from\ 75 to
160\ ms after tone is removed [as in\ \fIb)\fR ]; or
.LP
	ii)
	 the incoming tone ceases, in which case the split must be removed in 
the interval from\ 350 to 750\ ms after 
tone ceases;
.LP
\fR 	\fId)\fR 	when the signalling equipment is sending tone, a split
shall be introduced, if not already split, within 250\ ms of receipt of
an incoming tone.
.PP
The above requirements given in \fIa)\fR , \fIb)\fR , \fIc)\fR and\ \fId)\fR 
establish a transmitting path split at both ends of the circuit during 
the idle condition. 
.bp
.LP
.sp 2P
.LP
\fBRecommendation\ Q.313\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB2.3\ 2600\ Hz\ LINE\ SIGNAL\ RECEIVING\ EQUIPMENT\fR 
.FS
See also
Recommendation\ Q.112.
.FE
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.313''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.313	%'
.ce 0
.sp 1P
.sp 2P
.LP
2.3.1
	\fIOperate limits (tone\(hyon signals)\fR 
.sp 1P
.RT
.PP
The receiving equipment shall operate on a received tone signal, in the 
presence of the maximum noise expected on an international circuit, 
\(em40\ dBm0 uniform spectral energy over the range of\ 300 to 3400\ Hz, 
that meets the conditions listed below: 
.RT
.LP
	\fIa)\fR 	2600\ \(+-\ 15\ Hz;
.LP
	 \fIb)\fR to ensure proper operation in the presence of noise, the signal 
level of the initial portion of each tone\(hyon signal shall be 
augmented by 12\ dB (see \(sc\ 2.2.2).
.LP
.PP
As a result, the following requirement reflects both the augmented and 
steady\(hystate signal levels. The absolute power level\ \fIN\fR of each 
signal is within the limits (\(em27\ +\ \fIn\fR \ \(=\ \fIN\fR \ \(=\ \(em1\ 
+\ \fIn\fR )\ dBm where\ \fIn\fR is the 
relative power level at the input to the receiving equipment. The minimum
absolute power level \fIN\fR \ =\ (\(em27\ +\ \fIn\fR ) gives a margin 
of 7\ dB on the 
steady\(hystate nominal absolute power level of the received signal at 
the input to the receiving equipment. With augmentation the effective margin 
is increased from\ 7 to 19\ dB. 
.PP
The maximum absolute power level\ \fIN\fR \ =\ (\(em1\ +\ \fIn\fR ) gives 
a margin of 7\ dB on the augmented nominal absolute power level of the 
received signal at the input to the receiving equipment. 
.PP
The above tolerances are to allow for variations at the sending end
and variations in line transmission.
.PP
\fINote\fR \ \(em\ Since higher steady noise as well as impulsive noise 
may be encountered on intra\(hyregional circuits especially over certain 
compandored 
carrier systems, the maximum expected noise within a region must be taken 
into account in the design of equipment for that region. 
.RT
.sp 2P
.LP
2.3.2
	\fINon\(hyoperate limits\fR 
.sp 1P
.RT
.PP
1)
The receiving equipment shall neither operate on signals
originating from subscriber stations (or other sources) if the total power 
in the band from 800\ Hz to 2450\ Hz equals or exceeds the total power 
present at 
the same time in the band from 2450\ Hz to 2750\ Hz, as measured at the 
station, nor degrade these signals. Allowances shall be made in the receiving 
equipment design to accomodate expected deviations from these values due 
to attenuation distortion and carrier frequency shift on the total transmission 
path between the station and the receiving equipment. 
.sp 9p
.RT
.PP
2)
The receiving equipment shall not operate on any tone or signal whose absolute 
power level at the point of connection of the receiving 
equipment is (\(em17\ \(em20\ +\ \fIn\fR )\ dBm or less, \fIn\fR \ being 
the relative power 
level at this point.
.sp 9p
.RT
.LP
.sp 2P
.LP
2.3.3
	\fIRecognition of signals\fR 
.sp 1P
.RT
.PP
1)
System\ R1 must be protected against false signal recognition
caused by:
.sp 9p
.RT
.LP
	 \fIa)\fR signal simulation of tone\(hyon or tone\(hyoff signals by speech 
or other signals; 
.LP
	\fIb)\fR 	signal simulation of tone\(hyoff signals by momentary
interruptions of the transmission path.
.PP
The method of providing this protection is left to each
Administration concerned to allow for maximum flexibility in the implementation 
of the signalling and switching system design. However, the overall system 
requirements given in\ 2) and\ 3) below shall be met.
.LP
.sp 1
.bp
.PP
2)
The following requirements for signal recognition are specified
in terms of signal duration at the input to the signal receiving equipment 
and further assumes that signal levels, frequency and accompanying noise 
are within the limits specified in \(sc\ 2.3.1: 
.sp 9p
.RT
.LP
\fR 
	\fIa)\fR 	A 
tone\(hyon signal
lasting 30\ ms or less must be
rejected; that is, it must not be recognized as a signal.
.LP
	 \fIb)\fR A tone\(hyoff signal lasting 40\ ms or less must be rejected 
if the previous tone\(hyon signal is 350\ ms or longer; that is, it 
must not be recognized as a signal.
.LP
	\fIc)\fR 	Subsequent to establishing the cross office path, a
tone\(hyon ring\(hyforward (forward\(hytransfer) spurt signal
lasting
between\ 65 and 135\ ms must be recognized as a valid signal.
.LP
	\fId)\fR 	A tone\(hyon forward signal lasting 300\ ms or longer
must be recognized as a valid disconnect (clear\(hyforward) signal.
Prior to attaching a register, a forward tone\(hyon signal lasting
30\ ms or longer may be recognized as a valid disconnect
(clear\(hyforward) signal.
.LP
	\fIe)\fR 	To protect against a momentary interruption in the
transmission facility causing a continuous succession of false
connect (seizing) and disconnect (clear\(hyforward) signals,
.LP
the incoming equipment should be arranged to delay responding to
the second of two closely spaced connect (seizing) signals. The
timed delay introduced should be started at the end of initial
connect (seizing) signal or on recognition of the disconnect
(clear\(hyforward) signal. The delay introduced should be a
function of the round trip signalling time. For satellite
circuits the recommended time is 1300\ \(+-\ 100\ ms. For terrestrial
circuits the recommended time is 500\ \(+-\ 100\ ms. If the second
connect (seizing) signal persists beyond this timed interval,
the signal should be considered valid and a delay dialling
signal returned.
.LP
	\fIf\fR \fI)\fR 	Other tone\(hyon and 
tone\(hyoff signals
should  be recognized as valid signals, subsequent to the minimum limits
imposed by\ \fIa)\fR and\ \fIb)\fR above, as soon as possible.
.LP
.PP
\fINote\fR \ \(em\ Delays introduced by line signalling equipment should 
be held to a minimum consistent with the requirements covered herein to 
minimize signal transfer times. Minimizing the delay is especially important 
in the case of the answer signal and in the case of satellite circuit operation. 
In this 
latter case, if a hang\(hyup (clear\(hyback) signal has not been sent prior to
recognition of a disconnect (clear\(hyforward) signal, it is necessary that the
idle tone\(hyon signal, sent by the incoming exchange in response to the
disconnect signal, be recognized by the outgoing exchange prior to the 
elapse of the guard timing specified in Recommendation\ Q.317, \(sc\ 2.7.1. 
.PP
3)
The following signal simulation rates shall not be
exceeded.
.sp 9p
.RT
.LP
In the case when no answer signal is transmitted (non\(hycharged
calls), the simulation rates specified in \(sc\(sc\ 3\ \fIa)\fR and\ 3\ 
\fIb)\fR may, in some 
existing designs, be somewhat in excess of the values quoted.
.FE
.LP
	\fIa)\fR 	On the average not more than one false recognition of a
disconnect (clear\(hyforward) signal shall occur per\ 1500\ call hours 
of speech, at the \fIminimum\fR disconnect recognition time, as selected 
according to \(sc\ 2.3.3, 
2)\ \fIc)\fR and\ \fId)\fR . (In some older designs, this requirement may 
not be met, but for these cases the call hours figure must not be less 
than 500 
call
hours.)
.LP
	\fIb)\fR 	On the average, not more than one false ring\(hyforward
(forward\(hytransfer) signal shall occur per\ 70
call hours of
speech, at the \fIminimum\fR ring\(hyforward recognition time.
.LP
	\fIc)\fR 	Speech or other electrical signals as audible\(hytone
signals, with levels up to\ +10\ dBm0 shall not cause any false
simulation of answer signals.
.LP
	\fId)\fR 	The number and characteristics of false splits of the
speech path caused by speech or other signals shall not cause a
noticeable reduction in the transmission quality of the circuit.
.LP
.sp 1P
.LP
2.3.4
	\fIReceiving line split\fR 
.sp 9p
.RT
.PP
To prevent line signals of the signalling system from causing
disturbances to signalling systems on subsequent circuits, the receiving
transmission path to the connected exchange should be split when the signal
frequency is received to ensure that no portion of any signal exceeding 
20\ ms duration may pass out of the circuit. The use of a band\(hystop 
filter for 
splitting is necessary since in the case of non\(hycharged calls a continuous
signal tone persists in the return transmission path during conversation. 
The level of signal leak current transmitted to the subsequent circuit 
with the 
band\(hystop filter inserted
.bp
.PP
should be at least 35\ dB below the received  signal
level. In addition, the band\(hystop filter must not introduce more than 5\ dB
loss at frequencies 200\ Hz or more above or below the midband frequency nor
more than 0.5\ dB loss at frequencies 400\ Hz or more above or below the 
midband frequency. 
.PP
\fR The receiving line split must be maintained for the duration of the
incoming tone signal, but must cease within 300\ ms of tone removal.
.PP
\fINote\fR \ \(em\ In some existing designs, the initial cut may be a physical 
line disconnection but the filter must be inserted within 100\ ms of tone 
reception.
\v'2P'
.RT
.sp 2P
.LP
\fBRecommendation\ Q.314\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB2.4\ \fR \fBPCM\ LINE\ SIGNALLING\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.314''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.314	%'
.ce 0
.sp 1P
.PP
Individual channel line signalling is provided in the format of the CCITT 
primary multiplex operating at 1544\ kbit/s (Recommendation\ G.733). Designated 
signalling bits are marked\ 0 or\ 1 corresponding to tone\(hyon, 
tone\(hyoff in the single frequency in\(hyband arrangement as shown in 
Table\ 1/Q.311. As in the in\(hyband system, the same signalling state 
is 
used to indicate more than one signal by taking advantage of the fixed order
of occurrence of specific signals. The equipment must retain memory of the
preceding signal states and the direction of signals in order to differentiate 
between like state\ 0 and state\ 1\ signals. 
\v'2P'
.sp 1P
.RT
.sp 2P
.LP
\fBRecommendation\ Q.315\fR 
.RT
.sp 2P
.LP
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.315''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.315	%'
.sp 1P
.ce 1000
\fB2.5\ \fR \fBPCM\ LINE\ SIGNAL\ SENDER\fR \fB\ (TRANSMITTER)\fR 
.ce 0
.sp 1P
.sp 2P
.LP
2.5.1
	\fISignalling format\fR 
.sp 1P
.RT
.PP
The primary multiplex format is shown in Figure\ 1/Q.315. Per
channel, in\(hyslot signalling is accomplished by utilizing bit\ No.\ 8 
in each time slot of the designated frames (6,\ 12,\ etc.) for signalling 
purposes. Bit\ No.\ 8 of each time slot in the intervening frames (1\(hy5, 
7\(hy11,\ etc.) is used for 
encoding speech. Two signalling channels per speech channel are provided 
in the format. The multiframe alignment required for signalling purposes 
is obtained by subdividing the 8\ kbit/s framing pulse stream into two 
4\ kbit/s streams, one for terminal framing and one for signalling framing 
(S\(hybits). The relationship of the framing and multiframing signals to 
the signalling bits is given in 
Table\ 2/Q.315. Since only one line signalling channel is required for
System\ R1, the same signalling information is sent over both signalling
channels\ A and\ B.
.RT
.LP
.sp 1P
.LP
2.5.2
	\fITransmitted signal duration\fR 
.sp 9p
.RT
.PP
The transmitted signal durations are given in Table\ 1/Q.311 of
Recommendation\ Q.311.
.RT
.sp 1P
.LP
2.5.3
	\fITransmitting line split\fR 
.sp 9p
.RT
.PP
Since signalling is out\(hyband, no transmitting line split is
required.
.bp
.RT
.LP
.rs
.sp 22P
.ad r
\fBFIGURE 1/Q.315 p.2\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 25P
.ad r
\fBTableau [2/Q.315] p.3\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 2P
.LP
\fBRecommendation\ Q.316\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB2.6\ \fR \fBPCM\ LINE\ SIGNAL\ RECEIVER\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.316''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.316	%'
.ce 0
.sp 1P
.sp 2P
.LP
2.6.1
	\fIRecognition of signals\fR 
.sp 1P
.RT
.PP
System R1 must be protected against false signal recognition caused by 
signal simulation due to momentary loss of synchronization of the 
PCM\ system. The method of providing this protection is left to each
Administration concerned to allow for maximum flexibility in the implementation 
of the signalling and switching system design. However, the overall system 
requirements given below must be met.
.RT
.LP
	 \fIa)\fR A state\ 0 signal lasting 30\ ms or less must be rejected; that 
is, it must not be recognized as a signal. 
.LP
	 \fIb)\fR A state\ 1 signal lasting 40\ ms or less must be rejected if 
the previous state\ 0 signal is 350\ ms or longer; that is, it 
must not be recognized as a signal.
.LP
	\fIc)\fR 	Subsequent to establishing the speech path, a state\ 0
ring\(hyforward (forward\(hytransfer) signal lasting 65\(hy135\ ms must be
recognized as a valid signal.
.LP
	 \fId)\fR A state\ 0 forward signal lasting 300\ ms or longer must be 
recognized as a valid disconnect (clear\(hyforward) signal. Prior to attaching 
a register, a forward state\ 0 signal lasting 30\ ms or longer may be recognized 
as a valid disconnect (clear\(hyforward) signal. 
.LP
	 \fIe)\fR To protect against a momentary fault causing a continuous succession 
of false connect (seizing) and disconnect (clear\(hyforward) signals, the 
incoming equipment should be arranged to delay responding to the second 
of two closely spaced connect (seizing) signals. The time delay introduced 
.LP
should be started at the end of the initial connect (seizing)
signal or on recognition of the disconnect (clear\(hyforward)
signal. The delay introduced should be a function of the round
trip signalling time. For satellite circuits the recommended
time is 1300\ \(+-\ 100\ ms. For terrestrial circuits the recommended
time is 500\ \(+-\ 100\ ms. If the second connect (seizing) signal
persists beyond this timed interval, the signal should be
considered valid and a delay dialling signal returned.
.LP
	\fIf\fR \fI)\fR 	Other state\ 0 and state\ 1 signals should be
recognized as valid signals subsequent to the minimum limits imposed by\ 
\fIa)\fR and\ \fIb)\fR above, as soon as possible. 
.PP
\fINote\fR \ \(em\ Delays introduced by line signalling equipment should 
be held to a minimum consistent with the requirements covered herein to 
minimize signal transfer times. Minimizing the delay is especially important 
in the case of the answer signal and in the case of satellite circuit operation. 
In this 
latter case, if a hang\(hyup (clear\(hyback) signal has not been sent prior to
.LP
recognition of a disconnect (clear\(hyforward) signal, it is necessary that the
idle state\ 0 signal, sent by the incoming exchange in response to the
disconnect signal, be recognized by the outgoing exchange prior to the 
elapse of the guard timing specified in Recommendation\ Q.317, \(sc\ 2.7.1. 
.sp 1P
.LP
2.6.2
	\fIReceiving line split\fR 
.sp 9p
.RT
.PP
Since signalling is out\(hyband, no receiving line split is
required.
.RT
.sp 1P
.LP
2.6.3
	\fIAction on receipt of an alarm\fR 
.sp 9p
.RT
.PP
When the PCM primary multiplex has detected a fault and given an
alarm (see Recommendation\ G.733,\ \(sc\ 3.2) appropriate action shall 
be taken to 
remove automatically the affected circuits from service, and to terminate 
calls in progress, i.e.\ stop charging, release interconnected circuits,\ 
etc. When the alarm has been cleared the affected circuits should be automatically 
restored to service. 
.RT
.LP
.sp 2P
.LP
\fBRecommendation\ Q.317\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB2.7\ FURTHER\ SPECIFICATION\ CLAUSES\ RELATIVE\ TO\ LINE\ SIGNALLING\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.317''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.317	%'
.ce 0
.sp 1P
.PP
2.7.1
Access to the outgoing circuits shall be denied (guarded)  
.sp 1P
.RT
.LP
for 750\ to 1250\ ms (1050\ ms to 1250\ ms for satellite circuits) after 
initiation of the disconnect (clear\(hyforward) signal to ensure sufficient 
time for the 
release of the equipment at the incoming exchange. [See also the Note
to \(sc\ 2.3.3,\ 2) of Recommendation\ Q.313 and to \(sc\ 2.6.1 of
Recommendation\ Q.316.]
.bp
.PP
2.7.2
The disconnect (clear\(hyforward) signal may be sent at any time in the 
call sequence. 
.PP
2.7.3
The release of the chain of circuits in an established connection is only 
initiated from the originating exchange or the charge\(hyrecording 
exchange.
.PP
2.7.4
The start of metering the charge should be delayed by an
appropriate time after recording of the answer signal to prevent false 
charging resulting from possible false recognition of an invalid answer 
signal. 
.LP
.sp 2P
.LP
\fBRecommendation\ Q.318\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB2.8\ \fR \fBDOUBLE\ SEIZING\ WITH\ BOTH\(hyWAY\ OPERATION\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.318''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.318	%'
.ce 0
.sp 1P
.sp 2P
.LP
2.8.1
	\fIGeneral\fR 
.sp 1P
.RT
.PP
To minimize the probability of double seizing, the circuit
selection at the two ends of both\(hyway circuit groups should be such that, as
far as possible, double seizing can occur only when a single circuit of the
group remains free (e.g.\ by selection of circuits in opposite order at 
the two ends of the circuit group). 
.RT
.LP
.sp 1P
.LP
2.8.2
	\fIUnguarded interval\fR 
.sp 9p
.RT
.PP
In general the unguarded interval is small, except in the case of satellite 
operation where the circuit propagation time is long. However, 
System\ R1 does provide a means of detecting double seizing.
.RT
.sp 1P
.LP
2.8.3
	\fIDetection of double seizing\fR 
.sp 9p
.RT
.PP
In the event of double seizing, the incoming connect (seizing)
signal is recognized at each end as a delay\(hydialling signal. If a
start\(hydialling (proceed\(hyto\(hysend) signal is not received within 
the time\(hyout 
interval (e.g.\ 5\ seconds) double seizing is assumed.
.PP
In this event, either of the following arrangements may
apply:
.RT
.LP
	\fIa)\fR 	an automatic repeat attempt to set up the call; or
.LP
	 \fIb)\fR a recorder indication is given to the operator or to the calling 
subscriber and no automatic repeat attempt is made. 
.LP
.PP
With either method, means must be provided to ensure positive
release of the double seized circuit. To achieve the release it is recommended 
that the office which first assumes (based on timing) that dual seizure 
has 
occurred transmits a tone\(hyon (0\ state) signal followed by a tone\(hyoff 
(1\ state) signal before the final tone\(hyon (0\ state) signal (disconnect) 
is sent. The 
duration of initial tone\(hyon (0\ state) signal should be a minimum of 
100\ ms and a maximum of 200\ ms. The tone\(hyoff (1\ state) signal should 
be recognized as an unexpected tone\(hyoff (1\ state) signal at the distant 
end, after which the action specified in \(sc\ 3.6.2,\ 1)\ \fIc)\fR of 
Recommendation\ Q.325 applies. 
.LP
.sp 2P
.LP
\fBRecommendation\ Q.319\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB2.9\ \fR \fBSPEED\ OF\ SWITCHING\ IN\ INTERNATIONAL\ EXCHANGES\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.319''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.319	%'
.ce 0
.sp 1P
.PP
2.9.1
It is recommended that the equipment in international
exchanges shall have a high switching speed so that the switching time 
may be as short as possible. 
.sp 1P
.RT
.PP
2.9.2
At the outgoing, transit and incoming international exchanges,  
.LP
the seizing of the circuit and the setting up of the connection should take
place as soon as possible after receipt of the digits of the address that 
are necessary to determine the routing. 
.PP
2.9.3
At international exchanges the delay\(hydialling signal should be
returned as soon as possible after recognition of the connect (seizing) 
signal. The start\(hydialling (proceed\(hyto\(hysend) signal should be 
returned as soon as 
possible but in any case, the return should be before the time\(hyout of the
outgoing register. [See \(sc\ 3.6.2,\ 1)\ \fIa)\fR and\ \fIb)\fR of Recommendation\ 
Q.325.] 
.LP
.bp
.sp 1P
.ce 1000
\v'3P'
SECTION\ 3
.ce 0
.sp 1P
.ce 1000
\fBREGISTER\ SIGNALLING\fR 
.FS
As used in this
Section the term register includes traditional registers in
electromechanical exchanges and also the equivalent receiving device,
memory and logic in stored program exchanges.
.FE
.ce 0
.sp 1P
.sp 2P
.LP
\fBRecommendation\ Q.320\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB3.1\ 
\fBSIGNAL\ CODE\ FOR\ REGISTER\ SIGNALLING\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.320''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.320	%'
.ce 0
.sp 1P
.sp 2P
.LP
3.1.1
	\fIGeneral\fR 
.sp 1P
.RT
.PP
1)
Either semi\(hyautomatic working (with automatic machine or direct
operator access), or automatic working (with automatic machine access) may  
.sp 9p
.RT
.LP
be used for outgoing traffic. With automatic machine access the incoming
address signals are stored in a register until sufficient address information 
is received to route the call properly, at which time a free circuit may 
be 
selected and a connect (seizing) line signal sent. Subsequent to the
recognition of a delay\(hydialling line signal and a start\(hydialling
(proceed\(hyto\(hysend) line signal a KP (start\(hyof\(hypulsing) signal 
followed by the 
address and ST (end\(hyof\(hypulsing) signals are transmitted. The KP\ 
signal, which is nominally 100\ ms in duration, prepares the receiving 
equipment to accept 
subsequent register signals. The transmission of the KP\ signal should be
delayed by a minimum of 140\ ms, but not more than 300\ ms, after recognition 
of the start\(hydialling line signal. 
.PP
2)
Link\(hyby\(hylink register signalling applies.
.PP
3)
Register signalling is in a forward direction only and shall be
in accordance with the two\(hyout\(hyof\(hysix multifrequency code shown in
Table\ 3/Q.320. Three of the 15\ possible codes are unused in international
service and are available for special purposes.
.LP
.PP
4)
The receiving equipment must furnish a two\(hyand\(hytwo only frequency 
check on each received signal to ensure its validity. 
.sp 2P
.LP
3.1.2
	\fISending sequence of register signals\fR 
.sp 1P
.RT
.PP
1)
The sending sequence of address signals conforms to the
sequence indicated in Recommendation\ Q.107. However, for traffic within an
integrated world numbering zone (e.g.\ Zone\ 1) the language or discriminating
digit and country codes may have no application and may not be sent. In 
Zone\ 1, the sequence of signals sent from the operator or subscriber is 
as 
follows:
\v'3p'
.sp 9p
.RT
.LP
	a)
	\fISemi\(hyautomatic working for calls to a subscriber within\fR 
\fIZone\ 1:\fR 
.LP
	i)
	KP;
.LP
	ii)
	national (significant) number of the called subscriber;
.LP
	iii)
	ST.
.LP
.sp 2
.bp
.LP
	b)
	\fISemi\(hyautomatic working for calls to operators within\fR \fIZone\ 1:\fR 
.LP
	i)
	KP;
.LP
	ii)
	special decimal numbers;
.FS
The special numbers used to
reach operators are by agreement between Administrations.
.FE
.LP
	iii)
	ST.
\v'3p'
.LP
	c)
	\fIAutomatic working for calls to a subscriber within\fR 
\fIZone\ 1:\fR 
.LP
	i)
	national (significant) number of the called subscriber.
.PP
2)
The sending sequence of register signals shall conform to
Table\ 3/Q.320, noting the following:
.sp 9p
.RT
.LP
	\fIa)\fR 	a KP (start\(hyof\(hypulsing) signal shall precede the sequence
of signals in all cases;
.LP
	 \fIb)\fR the ST (end\(hyof\(hypulsing) signal shall follow the sequence 
of signals in all cases. 
.LP
.rs
.sp 17P
.ad r
\fBTABLE [3/Q.320], p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 2P
.LP
\fBRecommendation\ Q.321\fR 
.RT
.sp 2P
.ce 1000
\fB3.2\ \fR \fBEND\(hyOF\(hyPULSING\ CONDITIONS\fR \fB\ \(em\ REGISTER\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.321''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.321	%'
.ce 0
.sp 1P
.ce 1000
\fBARRANGEMENTS\ CONCERNING\ ST\ SIGNAL\fR 
.ce 0
.sp 1P
.PP
3.2.1
The register signalling arrangements shall provide for the
sending of an ST\ signal for both semi\(hyautomatic and automatic operation; 
the 
arrangements in the outgoing international register for recognizing the
ST (end\(hyof\(hypulsing) signal condition may vary as follows:
.sp 1P
.RT
.LP
.sp 1P
.LP
a)
	\fISemi\(hyautomatic operation\fR 
.sp 9p
.RT
.PP
The ST\ condition is determined by the receipt of the end\(hyof\(hypulsing 
signal initiated by the operator. 
.RT
.sp 1P
.LP
b)
	\fIAutomatic operation\fR \v'3p'
.sp 9p
.RT
.LP
	i)
	Where the ST\ condition is determined by the originating
national network, an ST\ signal is transmitted to the outgoing
international register. No further arrangements are
necessary in that register for this purpose.
.LP
	ii)
	 Where the ST\ condition is not received from the originating national 
network, the outgoing international register will be 
required to determine the ST\ condition. (See for example the
requirements for System\ No.\ 5, Recommendation\ Q.152,
\fIGreen\ Book\fR .)
.bp
.LP
.sp 2P
.LP
\fBRecommendation\ Q.322\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB3.3\ \fR \fBMULTIFREQUENCY\ SIGNAL\ SENDER\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.322''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.322	%'
.ce 0
.sp 1P
.PP
3.3.1
Signalling frequencies 700, 900, 1100, 1300, 1500 and 1700\ Hz. A signal 
shall consist of a combination of any two of these six frequencies. 
The frequency variation shall not exceed \(+- | .5% of each nominal frequency.
.sp 1P
.RT
.LP
.PP
3.3.2
Transmitted signal level \(em7\ \(+-\ 1\ dBm0 per frequency. The
difference in transmitted level between the two frequencies comprising 
a signal shall not exceed\ 0.5\ dB. 
.sp 9p
.RT
.PP
3.3.3
Signal frequency leak and modulation products
. The
level
of the signal leak current transmitted to the line should be at least:
.sp 9p
.RT
.LP
	\fIa)\fR 	50\ dB below the single frequency level when a
multifrequency signal is not being transmitted;
.LP
	 \fIb)\fR 30\ dB below the transmitted signal level of either of the two 
frequencies when a multifrequency signal is being 
transmitted. The modulation products of a signal shall be at least 30\ 
dB below the transmitted level of either of the two frequencies comprising 
the 
signal.
.sp 1P
.LP
3.3.4
	\fISignal durations\fR 
.sp 9p
.RT
.PP
KP signal: 100\ \(+-\ 10\ ms.
.PP
All other signals: 68\ \(+-\ 7\ ms.
.PP
Interval between all signals: 68\ \(+-\ 7\ ms.
.RT
.sp 1P
.LP
3.3.5
	\fICompound signal tolerance\fR 
.sp 9p
.RT
.PP
The interval of time between the moments when the two frequencies comprising 
a signal are sent must not exceed 1\ ms. The interval of time between the 
moments when the two frequencies cease must not exceed 1\ ms. 
\v'2P'
.RT
.LP
.sp 2P
.LP
\fBRecommendation\ Q.323\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB3.4\ \fR \fBMULTIFREQUENCY\ SIGNAL\ RECEIVING\ EQUIPMENT\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.323''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.323	%'
.ce 0
.sp 1P
.sp 2P
.LP
3.4.1
	\fIOperate limits\fR 
.sp 1P
.RT
.PP
The signal receiving equipment must operate satisfactorily on any combination 
of two of the frequencies received as a single pulse or train of 
pulses in the presence of maximum expected noise on an international
circuit, \(em40\ dBm0 uniform spectral energy over the range of 300\ to 
3400\ Hz, 
that meets the conditions listed below:
.RT
.LP
	 \fIa)\fR each frequency of the received signal is within \(+- | .5% of 
the nominal signalling frequency; 
.LP
	 \fIb)\fR the absolute power level\ \fIN\fR of each received frequency 
is within the limits 
.sp 1P
.ce 1000
(\(em14\ +\ \fIn\fR \ \(=\ \fIN\fR \ \(=\ +\ 0\ +\ \fIn\fR ) dBm
.ce 0
.sp 1P
.LP
	 where \fIn\fR is the relative power level at the signal receiver input. 
Assuming a nominal circuit loss of 0\ dB these limits give 
a margin of \(+- | \ dB on the nominal absolute level of each
received signal. Considering that a single equipment may
serve circuits whose designed loss (nominal loss) is greater
than\ 0\ dB (e.g.,\ circuits that are not equipped with echo
suppressors) account must be taken of the highest circuit
loss in the design of the receiving equipment (e.g.,\ by
increasing must\(hyoperate sensitivity) to ensure that the
minimum margin is 7\ dB;
.bp
.LP
	 \fIc)\fR the difference in level between the frequencies comprising a 
received signal is less than 6\ dB; 
.LP
	 \fId)\fR the signal receiving equipment must accept signals meeting the 
following conditions: 
.LP
	i)
	signals within the limits specified in\ \fIa)\fR , \fIb)\fR ,
and\ \fIc)\fR  | bove in the presence of maximum expected noise and
subject to the maximum expected delay distortion;
.LP
	ii)
	the duration of each frequency comprising a signal is
30\ ms or greater; and
.LP
	iii)
	the silent interval preceding the signal is 20\ ms or
greater.
.PP
The tolerances given in \fIa)\fR , \fIb)\fR , and\ \fIc)\fR  | re to allow for
variations at the sending end and in line transmission.
.PP
The test values indicated in\ \fId)\fR  | re less than the working values. 
The difference between the test value and the working values will allow 
for 
pulse distortion, variations in registration devices, etc.
.PP
\fINote\fR \ \(em\ Since higher steady noise as well as impulsive noise 
may be encountered on intraregional circuits, especially over certain compandored 
carrier systems, the maximum expected noise within a region must be taken 
into account in the design of equipment for that region. 
.RT
.sp 2P
.LP
3.4.2
	\fINon\(hyoperate limits\fR 
.sp 1P
.RT
.PP
1)
The receiving equipment shall not operate on any signal whose absolute 
power level at the point of the receiving equipment is 9\ dB or more 
below the must\(hyoperate sensitivity required to satisfy the conditions
established in \(sc\ 3.4.1\ \fIb)\fR .
.sp 9p
.RT
.PP
2)
The receiving equipment shall release when the signal level
falls 1\ dB below the level established in \(sc\ 1) above.
.LP
.PP
3)
Operation of the receiving equipment shall be delayed for a
minimum period necessary to guard against false operation due to spurious
signals generated internally on reception of any signal.
.PP
4)
The receiving equipment should not operate on a pulse signal of
10\ ms or less. This signal may be of a single frequency or two frequencies
received simultaneously. Likewise, after operation the equipment shall 
ignore short interruptions of the signal frequencies. 
.sp 1P
.LP
3.4.3
	\fIInput impedance\fR 
.sp 9p
.RT
.PP
The value of the input impedance should be such that the return
loss over a frequency range of 500\ to 2700\ Hz against a 600\(hyohm non\(hyinductive 
resistor in series with a two\(hymicrofarad capacitor is greater than 
27\ dB.
\v'2P'
.RT
.LP
.sp 2P
.LP
\fBRecommendation\ Q.324\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB3.5\ ANALYSIS\ OF\ ADDRESS\ INFORMATION\ FOR\ ROUTING\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.324''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.324	%'
.ce 0
.sp 1P
.PP
In the application of System R1 to intraregional networks, the routing 
plan of that network shall apply. The routing plan is such that 
analysis is limited to a maximum of six digits.
.sp 1P
.RT
.PP
\fINote\fR \ \(em\ An ISC processing an incoming call on a circuit using
System\ R1, if encountering a barred routing or unallocated number condition,
should preferably send the special information tone toward the originating
subscriber.
.bp
.LP
.sp 2P
.LP
\fBRecommendation\ Q.325\fR 
.RT
.sp 2P
.sp 1P
.ce 1000
\fB3.6\ RELEASE\ OF\ REGISTERS\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.325''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.325	%'
.ce 0
.sp 1P
.sp 2P
.LP
3.6.1
	\fINormal release conditions\fR 
.sp 1P
.RT
.PP
1)
An outgoing register shall be released when it has transmitted  the ST\ signal.
.sp 9p
.RT
.PP
2)
An incoming register shall be released on the forward
transmission of the ST\ signal to the next exchange, or when all pertinent
information has been transferred to an outgoing register.
.sp 2P
.LP
3.6.2
	\fIAbnormal release conditions\fR 
.sp 1P
.RT
.PP
1)
An outgoing register shall release in any of the following
situations:
.sp 9p
.RT
.LP
	\fIa)\fR 	on failure to recognize a delay\(hydialling signal within
5\ seconds of circuit seizure unless a longer interval is preferred for
particular traffic conditions;
.LP
	 \fIb)\fR on failure to recognize a start\(hydialling (proceed\(hyto\(hysend) 
signal within 5\ seconds of recognition of the delay\(hydialling signal 
unless a 
longer interval is preferred for particular traffic conditions;
.LP
	\fIc)\fR 	on recognition of an unexpected tone\(hyoff (0\ state) line
signal subsequent to the recognition of a start\(hydialling (proceed\(hyto\(hysend) 
signal, but prior to completion of outpulsing. This signal sequence will 
occur in the event of double seizing and therefore a repeat attempt may 
be invoked 
and as a result the register may not be released prior to completion of the
second attempt. (See Recommendation\ Q.318.);
.LP
	\fId)\fR 	on exceeding overall register timing of 240\ seconds.
.PP
2)
An incoming register shall release in any of the following
situations:
.sp 9p
.RT
.LP
	\fIa)\fR 	on failure to receive the KP\ signal within\ 10 to
20\ seconds of register seizure;
.LP
	\fIb)\fR 	on failure to receive the 1st through 3rd\ digits within
10\ to 20\ seconds of receipt of the KP signal;
.LP
	\fIc)\fR 	on failure to receive the 4th through 6th digits within
10\ to 20\ seconds of the registration of the 3rd\ digit;
.LP
	 \fId)\fR on failure to receive the remaining digits and ST\ signal within 
10\ to 20\ seconds of registration of the 6th\ digit; 
.LP
	\fIe)\fR 	on error detection such as receipt of one or more than
two frequencies in a pulse;
.LP
	 \fIf\fR \fI)\fR on failure to gain access to associated switching equipment 
within appropriate intervals of time. 
.PP
The timing intervals given in\ 1) and\ 2) above are representative values 
but need not necessarily apply to all types of switching systems or all 
traffic loads. 
.PP
An abnormal release of an outgoing register on failure to receive a
delay\(hydialling signal as discussed in 1)\ \fIa)\fR above, shall result 
in the 
circuit being locked out which maintains the tone\(hyoff (1\ state) condition
toward the distant end. The maintenance personnel should be alerted.
.PP
Abnormal releases should result in the return of an audible re\(hyorder 
(congestion) tone toward the originating end. If this condition (re\(hyorder) 
persists for more than 1\ to 2\ minutes, maintenance personnel should be
alerted.
.RT
.sp 2P
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\fBRecommendation\ Q.326\fR 
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.sp 2P
.sp 1P
.ce 1000
\fB3.7\ SWITCHING\ TO\ THE\ SPEECH\ POSITION\fR 
.EF '%	Fascicle\ VI.4\ \(em\ Rec.\ Q.326''
.OF '''Fascicle\ VI.4\ \(em\ Rec.\ Q.326	%'
.ce 0
.sp 1P
.PP
At all exchanges, the circuit shall be switched to the speech position 
when the registers (incoming or outgoing) are released. 
.sp 1P
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\fBMontage:\ \fR PAGE 20 = PAGE BLANCHE
.sp 1P
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