No dial tone when using DISA

checking the log i got the following:

Comfort noise support incomplete in Asterisk (RFC 3389). Please turn off on client if possible.

When I call the DISA extension directly, enter the password, I will get a dial tone that tells me that I can now dial the number I want to call. But when calling my asterisk DID from a PSTN line, I still get everything, when when accessing the extension, i don’t get a dial tone.

I checked the log, the above message is something that is related to the call.