Silence Suppression Problem with asterisk

Hello, Guys:
I try to connect to HuaWei softswitch. The HuaWei technical stuff said that I had to remove the Silence Suppression in asterisk. I check it is in chan_sip.c. But my asterisk is built with Tribox, which means i am using trtibox. but I can not find the chan_sip.c file and no idea to compile asterisk again in tribox. this is part of packet for testing.
v=0
o=root 1474 1474 IN IP4 XXX.XXX.XXX.XXX
s=session
c=IN IP4 XXX.XXX.XXX.XXX
t=0 0
m=audio 12774 RTP/AVP 18 101
a=rtpmap:18 G729/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=silenceSupp:off - - - -

Does anyone has a solution how to solve this problem?
Pleaase give me a hand !
thanks!
zhu8080

well this link is from the wiki.
bugs.digium.com/view.php?id=5374

Should do away with trixbox for this.