DTMF, G.711 and iLbc

Hi all,
I am a newbie to asterisk. Previously I have installed * 1.0.3 on a Linux Server for testing. In this testing environment, I encountered a problem. I am doing something like “Calling card application” which allow user to input the password and the number that user want to dial. But the main problem is the Planet VIP-450 SIP gateway simply doesn’t support SIP-INFO nor RFC2833. The only method is to try out G.711 with Inband DTMF, but seems the asterisk keep complaning… so i upgrade it to 1.2.1, the newest stable version. But I still got same error (WARNING of Inband DTMF is not supported on codec ilbc…)

Dec 13 23:42:06 WARNING[5337]: dsp.c:1422 ast_dsp_process: Inband DTMF is not supported on codec ilbc. Use RFC2833
Dec 13 23:42:06 WARNING[5337]: channel.c:2323 set_format: Unable to find a codec translation path from ilbc to ulaw
Dec 13 23:42:06 WARNING[5337]: channel.c:2323 set_format: Unable to find a codec translation path from ilbc to ulaw

It is very strange that it appears “ilbc” in the CLI.
In my sip.conf (here only involve SIP), I only put “disallow = all” and “allow=ulaw”. Even I remove “codec_ilbc.so” and “format_ilbc.so” from “/usr/lib/asterisk/modules/”.

So I am wondering how to “kill” this ilbc… although i know that iLbc really has low bandwidth usage, just around 13.3kbps itself…

Or any other solution that can solve this problem? (other than replacing the new VIP-450…)
Thanks very much!!!

Jason, Hong Kong