[asterisk-users] the sounds quality of IAX2 channels are not good as SIP channels?

[Ma Zhiyong]

I use both IAX2 channels and SIP channels. IAX2 channels reduce bandwidth effectively.

But sometime my cli show

NOTICE[1281]: chan_iax2.c:1628 iax2_destroy: Avoiding IAX destroy deadlock
WARNING[1281]: chan_iax2.c:708 jb_warning_output: Resyncing the jb.
last_delay 28, this delay 1227, threshold 1062, new offset -1227
WARNING[1281]: chan_iax2.c:6532 socket_read: Received trunked frame
before first full voice frame

And when concurrent calls are more than 30, IAX2 channels' sounds quality become poor.
I use codec ILBC both in SIP channel and IAX2 channel.Sounds always good
 when I use SIP protocol.

this is some of my configuration:
jitterbuffer=yes
forcejitterbuffer=no
;dropcount=2
;maxjitterbuffer=1000
;maxjitterinterps=10
;resyncthreshold=1000
;maxexcessbuffer=80
;minexcessbuffer=10
;jittershrinkrate=1
trunkfreq=30
trunktimestamps=yes
tos=reliability
codecpriority=host

It's same on both IAX2 side. Any idea?