asterisk users - May 2004 - ast_rtp_read: Unknown RTP codec 72 received

Hi,

i'd like to know more about this issue, i'm always getting this message
while in call with anyone from sip to  zap or zap to sip.
 ast_rtp_read: Unknown RTP codec 72 received

here is my current setup:
client side, x-lite, with the transmit silence to yes, using ulaw,alaw

on asterisk server side:
sip.conf contain allow=ulaw and allow=alaw
dtmfmode=inband

So i always get this anoying notice and i cannot find any doc about fixing it. I
have try to put rfc2833 or info for dtmfmode, still giving this result. Plus for
the one on the zap side (using a regular phone) , he is hearing me like crystal.
Me, using a sip x-lite phone software, i am always hearing parasite.

Thank in advance, i would really appreciate some help about this issue. Here is
my email for the one who know some of the answer : jfdube@sympatico.ca

Sincerely
JF