Level 3 signalling message
in SIF (Signalling Information Field)
Routing label
OpP
MaVP
MaFP
MTC
CIC
SLS
OPC
DPC
MTP ISUP
message:
SLS – 4 bit
CIC – 12 bit
Max 256 + 1
octets
ITU-T structure
ANSI => different
MTC: Message Type Code (name
of ISUP message)
MaFP: Mandatory Fixed Part
(no LI, no parameter names required)
MaVP: Mandatory Variable
Part (LI, no parameter names required)
OpP: Optional Part (LI and
parameter names required)
Structure of SS7 ISUP
message