GV Conferencing with XMPP Jabber connection

GV is setup with XMPP \ Jabber: inbound calls and outbound calls are working fine. I ran a test where a friend called my GV and I then tried to call in from my cellular. I heard a beeping \ tone when dialing on GV when I dialed from the cellular. I pressed the 5 key on GV phone, but it did not conference the cellular in. The cellular continued to ring the line and hear the beep \ tone on the GV and again tried pressing 5 to conference in the cellular.

Two Questions
I am not sure if the ‘5’ was received by Google Voice. Is this something I could see in Jabber Debug (I’m thinking ‘no’) or some other diagnostic method? The other question is has anyone had success conferencing others on a GV XMPP \ Jabber <==> Asterisk system?