SPA504G Transfer to BLF+SD key

Hi all,

I set up the line key 2 of a SPA504g to monitor/call an extension this way :

fnc=blf+sd+cp;[email protected]$PROXY;nme=Grandstream;vid=1

When I want to transfer the current call to extension 501 , I simply press that line key

The problem is this operation starts a BLIND transfer, my SPA is no more connected and the ext 501 is ringing while the caller is on hold.

Is there a way to start a regular attendant transfer when pressing a BLF/SD line key (to wait ext 501 answer and announce the call) ???

Does the feature depend from Asterisk or SPA configuration ??

Thank you very much.