Can I have conference with G.722?

I would like to make conference call with G.722.
I succeeded in making call from lifesize phone to another.
But I couldn’t connect it to MeetMe correctly.
I heard chopped voice from Asterisk.
Of course, when I specify G.711, I can hear voice correctly.

Can’t I have conference call with G.722?
I use Asterisk 1.42 and SIP Phone by Lifesize.