Re: [MMUSIC] Transport of "Flash-hook"

I believe to bring it back you would also need to define flashhook, unless you can find an international definition of the timings elsewhere and reference it.

In terms of timing, a disconnect with a timing of approximately 33% of a 100 ms cycle is a dial pulse (although I believe there are variants that work at twice this speed.

European standards indicate a duration of 50 - 130 ms for register recall.

Somewhere over 500 ms constitutes a hangup.

I believe I have seen PBX systems that have used the period between 130 ms and 500 ms as a second form of hookflash - no access to my early notes at the moment.

In more PBX related signalling systems a off hook to on hook of 140 - 290 ms can be a wink start to indicate starting to send digits.

So the problems are more than one type of hookflash exists, and probably a lack of definition of the timings in an international sense.

I'd also note that if we have "hookflash", why don't we have on-hook, off hook, dial pulse, and so on. 

Personally, as the hookflash is to gain access to something to transmit/receive digits, then maybe you should be turning the RTP DTMF channel on and off if you really want to simulate it!

Keith

-----Original Message-----
From: mmusic [mailto:mmusic-bounces@ietf.org] On Behalf Of Cullen Jennings (fluffy)
Sent: 09 June 2016 18:59
To: Brian Rosen
Cc: mmusic@ietf.org
Subject: Re: [MMUSIC] Transport of "Flash-hook"

I've see a lot of interop problems with hookflash. It's can be surprisingly hard for GWs to detect. Is there any way NENA could find a better way to do this? I'm not keen on bringing this back. 

> On Jun 2, 2016, at 1:02 PM, Brian Rosen <br@brianrosen.net> wrote:
> 
> Back in RFC2833, the DTMF tones section, code 16 was defined for “Flash”, the signal caused by a momentary depression of the hook-switch in a POTS phone.  When 2833 was obsoleted by 4733, flash was dropped, although the code 16 was reserved.
> 
> We have a use case in NENA (9-1-1 emergency stuff) where existing systems use flash interspersed wth tones in signaling dialing events which are not interpreted by the UA that receives them, but are instead transported to a device that creates appropriate SIP signaling for the dialing events initiated.  We have no other way to transport flash to interwork with our newer SIP based emergency calling systems.
> 
> I’m prepared to write a draft that restores code 16 for flash, as it was in 2833, but wanted to hear any objections to doing that.
> 
> Brian
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