My Asterisk box does not detect some DTMFs if I’m using some VoIP phone companies. I’m using “rfc2833” on my Asterisk box [/quote]
You should detect DTMFs only if they are coming to you over the legacy telephony interfaces or over uncompressed (G.711) VoIP calls.
In all other cases you should just receive DTMF information from your provider(s). They may use either rfc2833 or INFO. They may even have no support for DTMF information at all. The best way is to ask your provider(s). Second option - just check Asterisk debug information during the call.
You may have different DTMF settings on each trunk/provider you have and on the server globally. Asterisk will do conversion if necessary.