Cannot place an outgoing call using motif & Gtalk

Asterisk Asterisk Support
1

Hi all!
I have an Asterisk 11.8.1 installed on Debian wheezy, and I can’t place a GTalk outgoing call from it.
Here is my configuration:
motif.conf:

; Google Talk
[gtalk]
context=fromgtalk
disallow=all
allow=ulaw
transport=google
connection=gtalk

xmpp.conf:

[general]
debug=no
autoprune=no
;autoregister=yes
;collection_nodes=yes
;pubsub_autocreate=yes
auth_policy=accept

[gtalk]
type=client
serverhost=talk.google.com
;pubsub_node=pubsub.astjab.org
username=<gmail_user>@gmail.com/asterisk
secret=<password>
priority=25	
port=5222
usetls=yes
usesasl=yes
buddy=<friend_gmail_user>@gmail.com
;distribute_events=yes
status=available
statusmessage="Waiting for the call"
timeout=5
sendtodialplan=yes
context=gtalkmessage

I have configured a small test context, which dials my <friend_gmail_user> account when receiving any message from GTalk.
Here it is: context gtalkmessage { // This context is called when there is a message from GTalk account s => { Verbose("GTalk message received. Text: ${MESSAGE(body)}"); Dial("Motif/gtalk/<friend_gmail_user>@gmail.com",40,r); } }
And after Asterisk receives a chat message, the following happens:

    -- Executing [s@gtalkmessage:1] Verbose("Message/ast_msg_queue", ""GTalk message received. Text: test"") in new stack
GTalk message received. Text: test
    -- Executing [s@gtalkmessage:2] Dial("Message/ast_msg_queue", ""Motif/gtalk/<friend_gmail_user>@gmail.com",40,r") in new stack
[Apr  3 12:18:28] ERROR[26086][C-00000000]: chan_motif.c:1747 jingle_request: Motif channel driver requires an audio format when dialing a destination
[Apr  3 12:18:28] WARNING[26086][C-00000000]: app_dial.c:2437 dial_exec_full: Unable to create channel of type 'Motif' (cause 58 - Bearer capability not available)
  == Everyone is busy/congested at this time (1:0/0/1)
    -- Auto fallthrough, channel 'Message/ast_msg_queue' status is 'CHANUNAVAIL'

Does anybody know what sort of audio format is missing for motif?
By the way, incoming calls from GTalk work well.

Thanks in advance )