Voip problem - DTMF rfc2833 not working
Voip problem with DTMF
I have a Fortigate 60F and generally voip is working normal.
Except for the door-intercom.
The phones and the intercom are connected to an external sip server.
Calls can be made.
But to open the door, you have to response the call DTMF with dail 2 times zero.
Somehow the door-intercom don't received the DTMF code
If I call any other external number, with a IVR then DTMF is working normaly.
Now we change the DTMF standard in the phone to SIP INFO (RFC-2976) and not the default RFC2833
then the intercom is working. But tests to other external IVRs fail.
Of course i found things about the session helper.
But in the documentation also mentioned:
To use the SIP session helper you must not add a VoIP profile to the security policy. If you add a VoIP profile, SIP traffic bypasses the SIP session helper and is processed by the SIP ALG.
I have changed firewall policy's with voip profile strict / default / and without voip profile. no difference at all.
How to change the fortigate to working with RFC2833 ?