1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 ) TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%2!4%$G0G03%26)#%3G0G0$)4!,.%47/2+G0G0 )3$.G9)3$.G0G053%2G13.%47/2+G0G0).4%2 format errorsand operation errors 5.8Recovery Recovery from detected errors and informationoutputs to managements entity forunre
2、coverable errors 5.8Flow control Flow control by modulo and acknowledgement 3.6Broacast capability Provision of broadcast data links that areidentifiable by global TEI 3.3.4.1Functions Description Reference, Rec. I.451 (Q.931)Identify message andprocess messageTo recognize and validate the message f
3、ormats 4Call reference To identify the call request at the localuser-network interface 4.3Support messages A set of mandatory messages for basic callcontrol procedures 3Support information elements Specification of the message types 4.44 Fascicle III.8 - Rec. I.4703.3 A list of service related funct
4、ions is given below. Not all have yet been identified as related to a specific ISDNservice.a) Other terminal functionsTerminal equipment may include some of the following service dependent functions:- analogue-digital conversion- teleservice identification/selection- supplementary service identifica
5、tion/selection- stimulus to functional signalling conversion- storage/memory- code/rate translation- encryption-decryption- speech pattern recognition- speech synthesis- authorization checking- charge data recording- network maintenance data recording- network control capability service/maintenance- echo control- dialled number identification- bearer service identification/selection.b) Power- local power supply- power feeding- terminal energizing control- activation/deactivation.
