Firmware version: Any
Model: TE gateway
Call from TE gateway to SIP provider dropped after one hour.
Call flow: E1 provider----->TE200(SS7)---->SIP trunk---->SIP provider
As per SS7 log captured on TE gateway, it could see gateway sent REL to E1 provider after one hour on time, REL is similar to BYE in SIP.
Further check of SIP interaction with SIP provider, we could see the SIP provider sent BYE to gateway after one hour on time without reason. Also the SIP call transaction looks fine - Session Timer works fine. It's obvious that the issue the provider.
As per update from SIP provider at last, it is timeout restriction for one hour at their side, provider fixed the problem on their side.