TUP (Telephone User Part) – is being replaced by ISUP
ISUP (ISDN User Part) – for all signalling related to setting up, maintaining,
and releasing circuit switched connections
MAP (Mobile User Part) – for transactions between exchanges (MSC, GMSC)
and databases (HLR, EIR, AuC) in mobile networks
INAP (Intelligent Network Application Part) for IN applications in fixed
networks
CAP (CAMEL
Application Part) for extended IN functionality in mobile networks (where MAP is not sufficient ...)