call transfer in pjsua2

Question

I have a problem with call transfer using pjsua2 api. Actually I don't understand how this should be implemented for call transfer (REFER method).

My issue is on the transferee: when the transferee receives the REFER message, after sending NOTIFY to the transferor it creates the call to the transfer target: But the same Call class instance is used for both calls (the lookup method changes the id to match the searched id), while pjsua has 2 different call ids for the old and new calls. Therefore, when the transferee receives the BYE from the transferor, it deletes the Call instance which is used for both calls, whereas pjsua still keeps a reference to the new call with the target transfer, which ends with a program exception.

I implemented the onCallTransferRequest() callback in the transferee but I don't see what to do here (pjsua doesn't do anything in its similar callback...) My question is: how should I process this kind of transfer using pjsua2?

Thanks for your help and merry Christmas. Thibault

Answer 1

Unfortunately I am not expert in C++. If I may, I can explain you how to blind transfer an active SIP call generally in PJSUA2.

First of all you have to create CallOpParam-object with default call settings. Then, you have to call your current Call-object and transfer method on it. As I know, blind transfer method should take two (2) parameters, destination as a String and CallOpParam. You should specify destination as: sip:username@domain. Last thing you have to do is set a status code to your CallOpParam, it should be PJSIP_SC_DECLINE, and hang up your active Call.

After all that B and C partner should be able to talk.