./.WORLD TRADE
ORGANIZATIONG/TBT/Notif.99.168
19 April 1999
(99-1565)
Committee on Technical Barriers to Trade
NOTIFICATION
The following notification is being circulated in accordance with Article 10.6.
1. Member to Agreement notifying:  MEXICO          
If applicable, name of local government involved (Articles 3.2 and 7.2):           
2. Agency responsible: Federal Telecommunications Commission.  Ministry of
Communications and Transport.          
Agency or authority designated to handle comments regarding the notification shall be
indicated if different from above:  Enquiry Point
3. Notified under Article 2.9.2 [ X ], 2.10.1 [    ], 5.6.2 [    ], 5.7.1 [   ], other:           
4. Products covered (HS or CCCN where applicable, otherwise national tariff heading.
ICS numbers may be provided in addition, where applicable):  Interfaces          
5. Title, number of pages and language(s) of the notified document:  Draft Mexican Official
Standard PROY-NOM-151-SCT1-1999, Teleco mmunications – Interfaces – Message
Transfer Part of the Common Channel Signalling System (11 pages, Spanish).          
6. Description of content:  This Standard provides an overall view of common channel
signalling system No. 7, describing its various functional elements and the relationship
between them.  The Standard describes in general the functions and capacities of the
Message Transfer Part (MTP), the Signalling Connection Control Part (SCCP), the ISDN
User Part (ISDN-UP), the Transaction Capability (TC) and the Operation, Maintenance andAdministration Part (OMAP), except for the Te lephone User Part (TUP).  This Standard
includes a detailed description of the MTP.
The Standard specifies aspects such as the architecture of signalling system No. 7,
flow control and general criteria of compatib ility not specified in separate standards and
applicable to the entire signalling system No.7.
The overall purpose of signalling system No. 7 is to provide an internationally
standardized common channel signalling system (SS7) of general application:
- Optimized for functioning in digital telecommunication networks together 
with stored programme control exchanges;
- which can meet present and future information transfer requirements for
interprocessor dialogue within telecommunication networks for call control,
remote control and signalling of administration and maintenance;
- which offers a safe medium for information transfer in the correct sequence
and without loss or duplication.G/TBT/Notif.99.168
Page 2
Description of content:  (cont'd)
This signalling system meets the requirements of call control signalling for
telecommunication services such as telephony and circuit-switched data transmission, as
well as for use as a reliable system for the transfer of other types of information between
exchanges and specialized centres in telecommunication networks (for example, foradministration and maintenance purposes).  It is therefore used for multiple applications
both in specialized networks for specific services, such as networks capable of offering
multiple services.
The objective of signalling system No. 7 covers both circuit-related and non circuit-
related signalling.
Examples of applications of  signalling system No. 7 are:
-T S T N ;- ISDN;
- Interaction with network data bases and service control points;
- mobile communications (public land mobile network);
- network operation, administration and maintenance.
The signalling system is optimized to function on 64 kbit/s digital channels.  It is
suitable for point to point links, both earth and by satellite.  While it does not have the
special properties required for point to multipoint functioning, it may be expanded if
necessary for such an application.
The scope of this Standard is applicable  only to interconnection interfaces between
national public networks and the interfa ce between a national public network and an
international one.
This Standard is based on international recommendations ITU-T Q.700, ITU-T
Q.701, ITU-T Q.702, ITU-T Q.703, ITU-T Q .704, ITU-T Q.705, ITU-T Q.706 and ITU-T
Q.707 published in 1988 by the International Telecommunications Union.  In order to
maintain the original format of these recommendations, the same numbering of sections,figures and tables was retained, even though some sections, paragraphs and elements were
eliminated.
7. Objective and rationale, including the nature of urgent problems where applicable:  Safety  
        
8. Relevant documents:  Diario Oficial de la Federación  (Official Journal), 17 March 1999
9. Proposed date of adoption:
Proposed date of entry into force:To be determined
10. Final date for comments:  16 May 1999
11. Texts available from:  National enquiry point [ X ] or address, e-mail and telefax number of
the other body:           