[SIPForum-discussion] What is the function of telephone-event?

Tue Mar 18 07:34:47 UTC 2008

Hi Wong & Forum

Good day..!

Can u tell me how do you interpret the reference tags *[11]* in the RFCs as
per the below example...*[11] is referring to which document.*

for example :

The gateway SHALL also support SIP reliable provisional responses in
accordance with *[11]* as a UA.

Document source : draft-ietf-sipping-qsig2sip-04

Thanks & Regards
Rajeshkumar Babu
On Tue, Mar 18, 2008 at 5:50 AM, Wong Quan Fai Eugene NCS <
eugenewong at ncs.com.sg> wrote:

>  HI Andrea,
>
>
>
> The following extracted is from RFC2833. Hope it helps to answer your
> question,
>
>
>
> RTP packets using the payload format defined in this specification
>
>    are subject to the security considerations discussed in the RTP
>
>    specification (RFC 1889 [1]), and any appropriate RTP profile (for
>
>    example RFC 1890 [19]).This implies that confidentiality of the media
>
>    streams is achieved by encryption. Because the data compression used
>
>    with this payload format is applied end-to-end, encryption may be
>
>    performed after compression so there is no conflict between the two
>
>    operations.
>
>
>
>    This payload type does not exhibit any significant non-uniformity in
>
>    the receiver side computational complexity for packet processing to
>
>    cause a potential denial-of-service threat.
>
>
>
>    In older networks employing in-band signaling and lacking appropriate
>
>    tone filters, the tones in Section 3.14 may be used to commit toll
>
>    fraud.
>
>
>
>
>
> Best Regards,
>
> Eugene
>
>
>  ------------------------------
>
> *From:* discussion-bounces at sipforum.org [mailto:
> discussion-bounces at sipforum.org] *On Behalf Of *Andrea Puddu
> *Sent:* Monday, March 17, 2008 05:59 PM
> *To:* Mark Holloway; 'Steve Langstaff'; discussion at sipforum.org
> *Subject:* Re: [SIPForum-discussion] What is the function of
> telephone-event?
>
>
>
> Hi all,
>
> we have to perform some tests to verify the impact of using DTMF in-band
> with g729.
> Do you know which network performance parameters could affect the
> functioning of DTMF in-band with g729?
> For example ... jittering?delay?packet loss?what else?
>
> I am asking because it's not totally clear to me why DTMF in-band could
> not work together with g729.
>
> Thanks,
>
> Andrea
>
>
>
>  ------------------------------
>
> From: mh at markholloway.com
> To: androjoker at hotmail.com; steve.langstaff at citel.com;
> discussion at sipforum.org
> Subject: RE: [SIPForum-discussion] What is the function of
> telephone-event?
> Date: Thu, 6 Mar 2008 08:08:07 -0700
>
> G729 does not support inband DTMF because the codec compresses the audio.
> You must use out of band.  Therefore, telephone-event is used to tell the
> other endpoint how it should receive DTMF tones.  If you are using G711 you
> should be able to support inband.  If you are using a compressed codec you
> should consider using out of band.  This can be RFC 2833 or SIP Info
> Method.  Regardless, not supporting telephone-event reflects a poor SIP
> implementation in my opinion.
>
>
>
>
>
> *From:* discussion-bounces at sipforum.org [mailto:
> discussion-bounces at sipforum.org] *On Behalf Of *Andrea Puddu
> *Sent:* Thursday, March 06, 2008 7:09 AM
> *To:* Steve Langstaff; discussion at sipforum.org
> *Subject:* Re: [SIPForum-discussion] What is the function of
> telephone-event?
>
>
>
> Thanks Steve.
>
> Why did you talk about low bit-rate codec? I understood the matter about
> dtfm out of band, but it is not clear to me why it should impact low bit
> rate codec (e.g. g729).
>
> Thanks,
>
> Andrea
>
>
>  ------------------------------
>
> Subject: RE: [SIPForum-discussion] What is the function of
> telephone-event?
> Date: Thu, 6 Mar 2008 05:01:34 -0800
> From: steve.langstaff at citel.com
> To: androjoker at hotmail.com; discussion at sipforum.org
>
> "telephone-event" is a method for passing e.g. DTMF signalling in an RTP
> stream.
>
>
>
> The "101" (or any payload type in the range 96-127) refers to a
> dynamic payload type.
>
>
>
> So a stream that negotiates to use "101 telephone-event" may e.g. pass
> keypresses
>
> using RTP payload type 101 rather than "in-band".
>
>
>
> The risks you face in removing telephone event support are that if you are
> using a
>
> low bitrate codec such as G.729, or you are using equipment that does not
> expect
>
> to see DTMF "in-band" then users may lose the ability to control e.g. IVR
> equipment.
>
>
>  ------------------------------
>
> *From:* discussion-bounces at sipforum.org [mailto:
> discussion-bounces at sipforum.org] *On Behalf Of *Andrea Puddu
> *Sent:* 06 March 2008 12:15
> *To:* discussion at sipforum.org
> *Subject:* [SIPForum-discussion] What is the function of telephone-event?
>
> Hello guys,
>
> as the network here does not completely support "telephone event" in SDP
> they asked me to set up phones to not include "telephone event".
> I have looked at some RFCs .... but I couldn't understand what the
> telephone events are useful to.
>
> Do you see any risk to remove the telephone event, in particular the 101
> telephone event?
>
> thanks 1000.
>
> Andrea
>
>
>  ------------------------------
>
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-- 
Thanks & Regards

Rajeshkumar B
Engineer - Softswitch
Kuwait Network Technology
Email : rajeshkumarbin at gmail.com
Mobile : 00965-7278781
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