All drawings appearing in this Recommendation have been done in Autocad.
Recommendation E.401
STATISTICS FOR THE INTERNATIONAL TELEPHONE SERVICE
(NUMBER OF CIRCUITS IN OPERATION AND VOLUME OF TRAFFIC)
(Statistics exchanged by Administrations)
	Administrations exchange each year, in February, statistics showing the number of circuits used and the volume of traffic monitored in the preceding year, as well as estimates of the number of circuits which will be required three years and five years later. These statistics shall be drawn up in the form indicated below.
	A copy of the statistics shall be sent to the CCITT Secretariat for information.
ANNEX A
(to Recommendation E.401)
How to fill in the table on international telephone traffic statistics
Column 1			Designation of the connection by giving the name of the outgoing exchange first and then the name of the incoming exchange. Two–way connections will be shown in alphabetical order.
Columns 2 and 3		Number of circuits in operation as on 31 December of the year of the statistics.
				The number will be shown in column 2 when it refers to outgoing circuits and in column 3 when it refers to both–way circuits.
Columns 4 and 5		Number of circuits which would have been required during the year of the statistics.
Column 6			Method of operation.
				The following abbreviations will be used:
	A		for automatic,
	SA	for semiautomatic,
	M	for manual,
	A + SA	for automatic and semiautomatic.
Column 7			Destination of traffic.
				Each relation will be shown in this column on a separate line.
	In the example given, the traffic routed over the Zürich–København circuits is destined for Denmark (terminal), Sweden, Norway and Finland (transit). In this case, the data for each destination will be shown in columns, 8, 9, 10 and 11. The total traffic figure, however, should not be omitted. These data will be bracketed together. If the connection handles traffic only to the country in which the incoming exchange is situated, only the word “terminal” will appear in column 7.
Columns 8 and 9		Busy–hour traffic, expressed in erlangs. (See Recommendation E.600.)
	The traffic measured during the busiest month of the year of the statistics is given in column 9. For two–way circuit groups the total amount of incoming and outgoing traffic should be given. In column 8 the month of the year during which the traffic was measured should be indicated in roman numerals.

Column 10			Busy hour (UTC).
				This refers to the busy hour as defined in Recommendation E.600.
Column 11			Annual increase, in %. Each Administration should insert in this column the annual traffic increase rate with respect to the previous year.
Columns 12 and 13	Columns 12 and 13 should show the estimated number of circuits required to route traffic in three and five years' time, respectively. For example, if the statistics relating to 1982 are drawn up in February 1983, column 12 will give the estimated number of circuits required in 1986 and column 13 those required in 1988.

International telephone traffic statistics
Year: .............................................................
	Number of circuits in service	Number of circuit required	

Method of 	

Destination 	
Busy-hour traffic	

Start of busy-hour 	

Annual traffic 	Estimated number of circuit	

Observations	
Circuit	Out-going	Both-way	Out-going	Both-way	operation	of traffic	Month	Erlangs	hour (UTC)	increase	In three years	In five years		
1	2	3	4	5	6	7	8	9	10	11	12	13	14	
(Examples)														

Zürich-Kobenhavn	

24	

–	

20	

–	

SA	Terminal
Swedena)
Norway
Finland

Total	X
X
X
X

X	8
4
2
1

15	10.00
10.15
09.45
10.30

10.00	15%
12%
13%
7%

14%	

28	

32	a) Overflow traffic on Zürich-Stockhom connection	
Zürich-Stokholm	12	–		–	SA	Terminal	IX	5.5	10.15	12%	13	15