I am working on application using Freeswitch and SIP.js in which I need to detect if the call is being transferred.

The Sip.js application is actually an outbound dialer in which I load a list of phone numbers to call.

The application starts by calling people.

It is interesting to detect voicemail boxes. For that I am using mod_avmd.

My problem is when the other end transfers the call, the sip.js client should know that the current call is being transferred.

Is there a way that the original caller (sip.js client) knows that the call is being transferred?

I was looking at all the channel variables and I found that the RDNIS variable and the transfer_time variable are filled up when there is a transfer.