Transfer Call

Hi,
I need your help guys !!

The transfer is running fine, but only in one way, like :
When a SIP Phone A calls a SIP Phone B
B can transfer the call to SIP Phone C

But how can i do to allow A to transfer the call to C ?

I mean, the called phone can transfer the call, but I’d like the caller to do it.

Is there a way to do that ?

Thanks

Ok i found it
tT option