MTP functions
MTP level 1 (signalling data link level):
MTP level 2 (signalling link level):
MTP level 3 (signalling network level):
Physical
transmission (e.g. 64 kbit/s PCM time slot)
HDLC-type frame-based
protocol for flow control, error control (using ARQ), and signalling network supervision and
maintenance functions.
Routing in the
signalling network (using OPC, DPC) between SPs with level 4
users (see SIO at level 2).