How are you initiating the transfer? SIP native transfers are indistinguishable from a new call on a second line until the transfer is completed.
If your phones are capable of connected line presentation updates, and you enable it (sendrpid not no for chan_sip), the number will update when the transfer is completed.
I am not sure if i ve understand your question.
But i make an attended transfer.
The problem is that even in the history of the Sangoma phone in the details section it is not showing the callerid of the caller.
I meant did you press the transfer button/soft key on the phone, or did you dial the FreePBX transfer code/used a soft key configured to do that.
The phone isn’t really involved in the latter case, but in the former case, the way that SIP works is that the phone starts a separate call to the destination, as though it were a new call. None of the SIP phones I’ve used have sent remote party ID information for the associated incoming call. Only when the attended transfer is completed does a SIP phone tell the PBX that the incoming and outgoing calls are related.
Prefer the P-Asserted-Identity header, falling back to Remote-Party-ID, and finally to From, etc.
All except the first, when used, at the destination, with the appropriate Asterisk setting to send P-Asserted-Identity, or Remote-Party-ID, should result in the caller ID updating, on that destination phone, when the operator completes the transfer.