ISUP (Integrated Services User Part)
Essential for circuit-switching
related signalling
Features:
Establishment /
release of circuit switched connections (basic call control) using
link-by-link signalling
End-to-end
signalling between two exchanges (for this purpose SCCP + ISUP is
used)
General
(non-user-related) circuit management
Not only ISDN (can be generally used
in PSTN)
see Bhatnagar, p.77