Grandstream && send message

hi every body
I have two grandstream gxv3140 .they can connect with each other with audio and video.
now i want send message but i have this warning,and i can’t send.

[color=#0000BF]-- Executing [3006@calling2:3] Dial(“Message/ast_msg_queue”, “SIP/3006”) in new stack
[Oct 30 13:18:53] NOTICE[3911]: chan_sip.c:26770 sip_request_call: Asked to get a channel of unsupported format (nothing) while capability is (gsm|ulaw|alaw|h263|testlaw)
[Oct 30 13:18:53] WARNING[3911]: app_dial.c:2218 dial_exec_full: Unable to create channel of type ‘SIP’ (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’[/color]

there is my sip.conf

[color=#0000BF][3006]
type = friend
context =calling2
secret = 123456
username = 3006
host = dynamic
dtmfmode = rfc2833
callcounter=yes
busylevel=1
allowoverlap=no
callgroup=1
nat=yes
allow=all

[3012]
type = friend
context =calling2
secret = 123456
username = 3012
host = dynamic
dtmfmode = rfc2833
callcounter=yes
busylevel=1
allowoverlap=no
callgroup=1
nat=yes

allow=all[/color]

there is my extensions.conf

[color=#000080][calling2]
exten => _X.,1,NoOp(${EXTEN})
exten => _X.,n,Set(CALLERID(name)=“Omid”)
exten => _X.,n,Dial(SIP/${EXTEN})[/color]