In a user-user based calling on mobile apps, when the call is connected and the user moves from a Wifi to Mobile data (network change); the device sends a Re-Invite with new contact information and subsequent messages go to appropriate changed contact address.

But when the dialog is in say ringing state; and the caller moves from one network to another; what would be an appropriate SIP method to trigger the contact update. My problem is generating a Re-INVITE or an UPDATE before the call is connected is very difficult.

What I tried is sending an in-dialog INFO message with new contact address; which gets relayed to the called party and the response for INFO is also properly received on the new contact address. But the subsequent response of the INVITE like a 486 or 200 goes to the original contact only.

What would be the best way to update the contact address of a client if I'm maintaining all the dialogs in kamailio.

Thanks,

- Jayesh