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MTP functional diagram

	Signalling Link
Message _L _ Transtet Processing J-l Functions		;E,	User Message

Signalling Data Link Functions

•    Signalling Data Link is a bidirectional transmission path for transfer of signalling messages; two data channels operating together in opposite directions with the same data ratę

•    analog signalling link (4 kHz) accessible by modems

•    digital data links:

» 56 kbit/s (ANSI standard)

» 64 kbit/s (ITU-T standard)

•    minimum data ratę allowed is 4.8 kbit/s (delay requirements)

Signalling link functions

•    Correspond to the OSI’s data link layer (layer 2),

•    provide reliable transfer of signalling messages between two adjacent signalling points,

•    signalling units have variable length and are called “signal units”.