ITU-T Q.721 PDF

General

Use of Signalling System No. 7 for telephone call control signalling requires:

- application of Telephone User Part (TUP) functions, in combination with

- application of an appropriate set of Message Transfer Part (MTP) functions.

A general description of the signalling system and the division of functions between the Message Transfer Part and the Telephone User Part are presented in Recommendation Q.700 and the requirements of interaction between those two parts are contained in Recommendation Q.701.