Place a call via your Elastic SIP Trunk.

Call transfer call flow in sip. The following image shows the basic call flow of a SIP session. Also this document covers the SIP Troubleshooting commands. The first flow consists of all the SIP requests and responses between Kevin and Mike.

REFER is used to instruct a SIP carrier to move a trunk call to an off-PBX destination. But in each case where an attended transfer may be possible a semi-attended transfer is possible. A blind transfer is one in which the transferring phone connects the caller to.

The second flow consists of Kevins call to Wayne. The combined flow can be divided into six parts. Without REFER inbound and outbound trunks would be tied up for the duration of the call even after the transfer was completed.

Setup PBX A SIP IP Phone User A GW1 IP Network User B. SIP provides a mechanism for transferring calls from one User Agent UA to another. The proxy server sendsa 100 Trying response immediately to the caller Alice to stop the re-transmissions of the INVITE request.

User B answers the call. Check your Twilio Call Log in the Console to confirm the transfer worked as requested and to see all relevant call details. The term Semi-Attended transfer comes from BroadSoft Inc.

Twilio will receive that request transfer your call. Once established initiate a call transfer from your phone. A redirect is when a UA doesnt answer the call but simply informs the callee to resend the INVITE to another SIP URI.