AMP General Settings - Play Extension Number

I have the “Play extension number when transferring a call” box checked in AMP General Settings but Asterisk does not play the extension number when transferring the call. Can someone tell me how to make this happen?

When someone presses one on my IVR it is setup to route the call to extension 900. Preferrably, what I’d like to happen is for the system to tell the caller that the call is being transferred and for music to play until the call is answered.


custom app field? then put something in extensions_custom.conf?