[Blink] [solved] Inband DTMF

Wilhelm Wimmreuter wilhelm at wimmreuter.de
Sat Dec 5 17:05:25 CET 2009

Thanks to the hints of Iñaki Dan and Adrian I have got it working again.

.. it was my strange setup with b2b UAs and a fritz box used as a PSTN gateway.

 I could hear DTMF on a local call and after this I just had to open
my ports (50000-5400) on the b2bUA again and all was done.


  Blink ---> b2bUA ---> Fritz-Box ---> PSTN Conference-Bridge
     |                                 (freeconference.com)
     +-----> Local endpoint 
             (Siemens VoIP 674IP DECT Phone) 

Thaks for the hints


On 03.12.2009, at 19:22, Adrian Georgescu wrote:

> Hi Willi,
> Inband DTMF has been deprecated long time ago. The agreed standard for sending DTMF is RFC 2833 and Blink supports this method. I know that there is lot of legacy PBX out there still doing SIP INFO and inband DTMF but there is little we can do about this.
> Even if Blink would support multiple types of DTMF sending, which will most likely won't because of the intrinsic technical hurdles involved, to support legacy devices you would still face the issue that it cannot be negotiated before hand so you must manually set the client every time differently. What works with legacy vendor A will not work with legacy vendor B. The last RFC is the answer and everyone need to upgrade their product to support it sooner or later.
> --
> Adrian
> On Dec 2, 2009, at 4:38 PM, Wilhelm Wimmreuter wrote:
>> Hmm,
>> is there a possibility to send inband DTMF with blink?
>> Just tried out a conference bridge and I failed?
>> Willi
>> _______________________________________________
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