I have a SIP trunk connected to a Front Range IVR (HEAT System). We send calls down the HEAT SIP trunk, everything works great! But when a Heat operater tries to forward a call back out the Heat SIP trunk to a VoIP phone or Cell Phone the call disconnects.
Where should I look to trouble shoot this. the CSS looks fine, and the original connects without issue.
I guess you're on a CallManager system as you mentioned CSS, so ensure you have SIP tracing enabled in the trace settings for the primary subscriber node and then pull the CCM traces.
If you are feeling rash (and haven't tried this already) try forcing an MTP on the SIP trunk; you would need to ensure you have an MTP in the MRGL associated with the trunk and be running G711 if its' the CallManager built-in software MTP.
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