I'm using the OpenSIPS B2BUA scenario that handles REFER messages. It works well for the first REFER transfer but if someone tries to transfer a second time it doesn't work.
Here is the issue I am seeing (my siptraces will have the same users)
PSTN User 15X26X65XX5 calls the OpenSIPS user 90188X9XX0 OpenSIPS user 90188X9XX0 answers the call and then transfers to OpenSIPS user 9000 OpenSIPS user 9000 picks up the call and then tries to transfer the call back to OpenSIPS user 90188X9XX0
This is where it messes up. When user 9000 tries to transfer the call again I see that the OpenSIPS B2BUA server receives the REFER message but before the B2BUA sends the 202 ACCEPTED message like the "refer script" tells it to it first sends an INVITE message that doesn't look complete compared to the INVITE that was sent the first time 90188X9XX0 did a REFER. I have no clue why this INVITE message is getting generated and sent from the B2BUA server before the 202 ACCEPTED is sent. Also in the INVITE message you will see that the RURI and To: header say 9000@domain. It really should be 90188X9XX0@domain since that is who I am transferring to.