[Freeswitch-users] DTMF: liberal-dtmf=true vs dtmf_type=none

[Richard Brady]

Hi folks

I am try to prevent DTMF tones from being transmitted from one channel to
another on a bridge by adding the following:

  <action application="export" data="nolocal:dtmf_type=none"/>

This will prevent tones from the inbound channel from being transmitted on
the outbound channel. Nifty!

However, it also prevents RFC2833 from being advertised on the outbound
channel and this is problematic in cases where suppression is required in
the forward direction but not the reverse.

Setting liberal-dtmf=true on the profile does not help, it appears that
dtmf_type=none in the dialplan (or dtmf-type=none in the profile) overrides
liberal-dtmf in the profile.

I would like to file a bug arguing that liberal-dtmf has inconsistent
behaviour. For example, it will override the dtmf-type=none
profile parameter in SDP offers but not in SDP answers. It makes sense that:

* dtmf-type/dtmf_type should influence offers and answers alike, as well as
what is used for outgoing DTMF and what is recognised as incoming DTMF, and
* liberal-dtmf should override dtmf-type for offers and answers alike, as
well as for what is recognised as incoming DTMF, but
* liberal-dtmf should not override what is sent as outgoing DTMF, since
that would make the dtmf-type parameter completely impotent.

Does anyone have any thoughts / suggestions / rebuttals?

Thanks,
Richard

FreeSWITCH Version 1.3.0+git~20121002T220322Z~d84df73aaa (git d84df73
2012-10-02 22:03:22Z)
Vanilla config except for addition of the above line to Local_Extension in
default.xml dialplan.
Ubuntu 12.04.1 LTS
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