[SIPForum-techwg] Comment on section 16.3 (DTMF)

[Elwell, John]

We run up against the architectural problem again when we talk about the
Media Endpoint doing SDP offer/answer.

I previously proposed the following text and I though Francois agreed,
so why can't we adopt this?

"A SIP-PBX or SP-SSE MUST advertize support for RFC 4733 in it's SDP on
behalf of any Media Endpoint that supports receiving DTMF digits. 

Any Media Endpoint that supports sending DTMF MUST use the RFC 4733
procedures, provided that the other side has advertized support for
receiving RFC 4733 in the offer/answer exchange."

John
 

> -----Original Message-----
> From: Francois Audet [mailto:audet at nortel.com] 
> Sent: 14 April 2009 23:19
> To: Spencer Dawkins; Elwell, John; techwg at sipforum.org
> Subject: RE: [SIPForum-techwg] Comment on section 16.3 (DTMF)
> 
> I don't think the phrase "supports the transport of DTMF tones" makes 
> any sense.  That whole second paragraph is unclear on who is 
> sender who is
> receiver. I would reword the second paragraph as follows:
> 
> "Any Media Endpoint that supports the reception of DTMF tones 
> MUST support the negotiation via an SDP offer/answer of the 
> supported method used to transmit the tones. The Media 
> Endpoint transmiting the RTP payload MUST use the dynamic RTP 
> payload type advertized in the SDP by the Media Endpoint 
> advertizing support
> for receiving RFC 4733 packets."
> 
> And the third paragraph:
> 
> "Any Media Endpoint that supports sending DTMF MUST use the 
> RFC 4733 procedures to transmit DTMF tones using the RTP 
> telephone-event payload format, provided that the other side 
> has advertized support for receiving RFC 4733 in the 
> offer/answer exchange."
> 
> > -----Original Message-----
> > From: Spencer Dawkins [mailto:spencer at wonderhamster.org] 
> > Sent: Tuesday, April 14, 2009 15:09
> > To: Audet, Francois (SC100:3055); Elwell, John; techwg at sipforum.org
> > Subject: Re: [SIPForum-techwg] Comment on section 16.3 (DTMF)
> > 
> > I think the final text you guys are talking about looks 
> > roughly like this:
> > 
> > "A SIP-PBX or SP-SSE MUST advertize support for RFC 4733 in 
> > its SDP on behalf of any Media Endpoint that supports 
> > receiving DTMF digits.
> > 
> > "Any Media Endpoint that supports the transport of DTMF tones 
> > MUST support the negotiation via an SDP offer/answer of the 
> > supported method used to transport the tones. The Media 
> > Endpoint MUST support the ability to use any dynamic RTP 
> > payload type when negotiating the use of RFC 4733.
> > 
> > 
> > "Any Media Endpoint that supports sending DTMF MUST use the 
> > RFC 4733 procedures to transport DTMF tones using the RTP 
> > telephone-event payload format, provided that the other side 
> > has advertized support for receiving RFC 4733 in the 
> > offer/answer exchange."
> > 
> > 
> > 
> > Does this work for  people?
> > 
> > 
> > 
> > Thanks,
> > 
> > 
> > 
> > Spencer
> > 
> > 
> > 
> > ----- Original Message -----
> > From: "Francois Audet" <audet at nortel.com>
> > To: "Elwell, John" <john.elwell at siemens-enterprise.com>;
> > <techwg at sipforum.org>
> > Sent: Thursday, April 09, 2009 3:47 PM
> > Subject: Re: [SIPForum-techwg] Comment on section 16.3 (DTMF)
> > 
> > 
> > > Yep.
> > >
> > >> -----Original Message-----
> > >> From: Elwell, John [mailto:john.elwell at siemens-enterprise.com]
> > >> Sent: Thursday, April 09, 2009 13:22
> > >> To: Audet, Francois (SC100:3055); techwg at sipforum.org
> > >> Subject: RE: [SIPForum-techwg] Comment on section 16.3 (DTMF)
> > >>
> > >>
> > >>
> > >> > -----Original Message-----
> > >> > From: Francois Audet [mailto:audet at nortel.com]
> > >> > Sent: 09 April 2009 19:33
> > >> > To: Elwell, John; techwg at sipforum.org
> > >> > Subject: RE: [SIPForum-techwg] Comment on section 16.3 (DTMF)
> > >> >
> > >> > I think the wording is kind of awkward.
> > >> >
> > >> > The real point is that IF you need to either send or
> > >> receive (or both)
> > >> > DTMF, it must be done using RFC 4733. Typically, phones 
> > for example 
> > >> > don't need to be able to receive DTMF. Some specialized 
> > devices may 
> > >> > not have to send them either (e.g., a hot-line phone with
> > >> no keypad,
> > >> > etc.).
> > >> >
> > >> > What about:
> > >> >
> > >> > Any Media Endpoint in the Enterprise network or Service 
> > Provider's 
> > >> > network that support receiving DTMF digits MUST advertize
> > >> its support
> > >> > for RFC 4733 in it's SDP in an Offer or Answer as appropriate.
> > >> >
> > >> > Any Media Endpoint that supports sending DTMF MUST use 
> > the RFC 4733 
> > >> > procedures, provided that the other side has advertize 
> > support for 
> > >> > receiving RFC 4733 in the Offer/Answer exchange.
> > >> >
> > >> > Note that there is no advertizing of the ability to send 
> > RFC 4733; 
> > >> > only the ability to receive RFC 4733.
> > >> [JRE] Fine, but this is not quite in accordance with the 
> > >> architecture, where the SIP-PBX or SP-SSE does the 
> > signalling and the 
> > >> media endpoint does the RTP. To correct this I would say:
> > >>
> > >> "A SIP-PBX or SP-SSE MUST advertize support for RFC 4733 
> > in it's SDP 
> > >> on behalf of any Media Endpoint that supports receiving 
> > DTMF digits.
> > >>
> > >> Any Media Endpoint that supports sending DTMF MUST use the 
> > RFC 4733 
> > >> procedures, provided that the other side has advertized 
> > support for 
> > >> receiving RFC 4733 in the offer/answer exchange."
> > >>
> > >> John
> > >>
> > >> >
> > >> >
> > >> > > -----Original Message-----
> > >> > > From: techwg-bounces at sipforum.org 
> > >> > > [mailto:techwg-bounces at sipforum.org] On Behalf Of 
> Elwell, John
> > >> > > Sent: Thursday, April 09, 2009 06:20
> > >> > > To: techwg at sipforum.org
> > >> > > Subject: [SIPForum-techwg] Comment on section 16.3 (DTMF)
> > >> > >
> > >> > > 1. "Any Media Endpoint in the Service Provider's network
> > >> MUST also
> > >> > > support the ability to transport DTMF tones using the RTP 
> > >> > > telephone-event payload format as described in RFC 4733
> > >> when using
> > >> > > any codec.
> > >> > > Any Media Endpoint in the Enterprise network that
> > >> originates and/or
> > >> > > terminates voice traffic MUST support RFC 4733."
> > >> > >
> > >> > > Why are requirements slightly different for the two sides.
> > >> > > Should we combine these statements:
> > >> > > "Any Media Endpoint in the Enterprise network or Service
> > >> Provider's
> > >> > > network MUST also support the ability to transport DTMF
> > >> tones using
> > >> > > the RTP telephone-event payload format as described in
> > >> RFC 4733 when
> > >> > > using any codec."
> > >> > >
> > >> > > 2. Concerning this same text, this doesn't explicitly
> > >> make provision
> > >> > > for media endpoints that can transport DTMF but do 
> not need to 
> > >> > > receive it.
> > >> > > So should we add the sentence:
> > >> > > "This applies to transmission and, if applicable,
> > >> reception of DTMF
> > >> > > tones."?
> > >> > >
> > >> > > 3. "Any Media Endpoint in the Enterprise network that
> > >> supports the
> > >> > > transport of DTMF tones MUST support the negotiation 
> > via an SDP 
> > >> > > offer/answer of the supported method used to transport 
> > the tones."
> > >> > > Shouldn't this apply to SP endpoints too? A text proposal
> > >> for this
> > >> > > is in an earlier email dealing with architecture.
> > >> > >
> > >> > > John
> > >> > >
> > >> > > _______________________________________________
> > >> > > techwg mailing list
> > >> > > Send mail to: techwg at sipforum.org Unsubscribe or edit 
> > options at:
> > >> > > http://sipforum.org/mailman/listinfo/techwg
> > >> > >
> > >> >
> > >>
> > >
> > > _______________________________________________
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> > > 
> > 
> > 
> > 
>