[OpenSIPS-Users] Session expires, calls disconnect

[Schneur Rosenberg]

I never really understood how the session expires works and whats the
difference between UAC or UAS, who is supposed to send the reinvite?
etc, if anyone can provide me with a simple explanation I would really
appreciate.

I'm getting a call from a DID which has Expires: 240. Min-SE: 1200 in
the sip headers. the call gets disconnected at exactly 30 minutes,
because I'm not sure how the Expires works I don't know what do, is
opensips responsible to send the reinvite or the phone? if opensips is
supposed to initiate the INVITE what module and functions do I need to
use.

thanks in advance
S. Rosenebrg