ITU-T M.570-1989 Constitution of the Circuit: Preliminary Exchange of Information - General Maintenance Principles - Maintenance of International Transmission Systems and Telephone Circuits (Study Group IV) 5 pp
As soon as it is decided to bring a new circuit into operation, the technical services of the terminal
countries should agree upon the circuit control station, and the technical service of each transit country should
advise the other technical services concerned of the name of the sub-control station chosen for its territory. If the
circuit is routed in a direct group or block crossing a transit country without demodulation or demultiplexing, no
sub-control station need be provided for the transit country. When a circuit is subjected to analogue-to-digital
conversion using, for example, a transmultiplexer, the location of the transmultiplexer should be designated as
circuit sub-control station.
Also the technical services of all the countries concerned should send to the technical service responsible
for the circuit control station information which will be required for the preparation of the circuit routing form
(see the Appendix I to this Recommendation) using the letter and number code on the form. The information for
a circuit without audio sections will consist of the numbers of the groups or blocks used and the number of the
channel in each group or block.
In the case of a both-way circuit, the circuit order of selection should be stated, including the method by
which the International Switching Centre selects circuits (i.e., sequentially by circuit, fully randomly or sequentially
by block of circuits but randomly within the block, etc.).
When the circuit is assigned its designation (according to Recommendation M.140, 0 i), the Administration
with control station responsibility will assemble the necessary technical and operational information. This
should be entered into the list of Related Information (as defined in Recommendation M.140, 0 2) which consists
of the items shown in Annex A.
ITU-T M.570-1989 history
1989ITU-T M.570-1989 Constitution of the Circuit: Preliminary Exchange of Information - General Maintenance Principles - Maintenance of International Transmission Systems and Telephone Circuits (Study Group IV) 5 pp