My provider has recently upgraded their back end system and I am starting to see failed REGISTER requests from my 3CX due to invalid digest response. After capturing and tracing the SIP handshake traffic, I have noticed a different Contact URI parameter is used: instead of the normal "rinstance=some_random_hex" field, the successful REGISTER request (from their SIP device) has "line=xxxxx" in the Contact URI parameter. And the xxxxx seems to be tied to my account, as it remains the same throughout different sessions. Obviously the next logical step is to configure 3CX to behave like the provider's SIP device by sending the same parameter. But I do not see the Contact URI parameter as a changeable variable in the current 3CX version. Is there a way I can manipulate this to the desired string? Thank you!