[SIPForum-discussion] Does every Voip phone use SIP INFO to send DTMF?

[Paul Kyzivat]

On 8/27/15 10:07 AM, Rodrigo Pimenta Carvalho wrote:
> Hi Paul.
>
> Thank you for discussing.
>
> The SIP INFO will be sent always during an ongoing call. So, it will not be instead of a SIP INVITE.
>
> "It sounds like a proprietary mechanism for turning sip phone into a dumb
> endpoint so that the server can handle all the logic." You are right.
>
> During a conversation, the person in the Voip Phone will have to dial "200", for example. Such number will work like a command to open the door where is the peer (other person asking to enter in a house, for example). So, the dialed number 200 will be sent to the SIP Proxy (in this case OpenSIPS). The SIP Proxy will just forward this value (SIP INFO message) to the peer´s softphone.  Such target softphone will interpret the SIP INFO and then interact with the door hardware to unlock the door.

Maybe I misunderstood.

So you are saying that INFO is being used for transmitting  DTMF within 
a call, instead of 2833 or KPML?

If so, depending on what format is being used, it is pretty common, 
though non-standard.

2833 (DTMF in media) is the preferred way. If you must use DTMF in 
signaling, then KPML is the "standard" way. But it never got much of a 
foothold. Use of INFO got an early, though proprietary start, and has 
lingered.

	Thanks,
	Paul

> I have tested it using the Voip Phone Leucotron, made in Brazil.
> As long as the target softphone will accept only SIP INFOs, so our project will accept only Voip Phones able to send SIP INFOs, as a requirement.
>
> Can you see some problem with this use case?
>
> Any hint will be very helpful.
>
> Regards.
>
>
> RODRIGO PIMENTA CARVALHO
> Inatel Competence Center
> Software
> Ph: +55 35 3471 9200 RAMAL 979
>
> ________________________________________
> De: discussion-bounces at sipforum.org <discussion-bounces at sipforum.org> em nome de Paul Kyzivat <pkyzivat at alum.mit.edu>
> Enviado: terça-feira, 25 de agosto de 2015 13:16
> Para: discussion at sipforum.org
> Assunto: Re: [SIPForum-discussion] Does every Voip phone use SIP INFO to send DTMF?
>
> On 8/24/15 2:26 PM, Rodrigo Pimenta Carvalho wrote:
>> Hi.
>>
>>
>> In my office I have a Voip phone. During a call with such device,
>> whether I dial 200 for example, the phone will generate a SIP INFO
>> message containing the value 200. Good!
>>
>>
>> Does every Voip phone send DTMF values as SIP INFO messages? Is it in
>> general  a kind of standard in the telecommunications? Or is it a matter
>> of some device configuration?
>
> No, this is not standard. Is this *instead* of sending an INVITE? Or in
> addition?
>
> It sounds like a proprietary mechanism for turning sip phone into a dumb
> endpoint so that the server can handle all the logic.
>
> What voip server system and handset do you have?
>
>          Thanks,
>          Paul
>
>> Any hint will be very helpful!
>>
>> Best regards.
>>
>>
>> ​RODRIGO PIMENTA CARVALHO
>> Inatel Competence Center
>> Software
>> Ph: +55 35 3471 9200 RAMAL 979
>>
>>
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