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

If the purpose of this comment is to force everyone to be compliant with your 40 year old system, which you acknowledge you want to change out anyway, then that seems to be a very poor justification.

I would note that if you need to specify interoperability, the the old version still exists - it has not disappeared just because another document has replaced.

To me, you need to justify this based on a need for interoperability of new equipment in the field.

Keith

-----Original Message-----
From: mmusic [mailto:mmusic-bounces@ietf.org] On Behalf Of Brian Rosen
Sent: 10 June 2016 14:21
To: Cullen Jennings (fluffy)
Cc: mmusic@ietf.org
Subject: Re: [MMUSIC] Transport of "Flash-hook"

I have a system that has been in use for 40 years.  We’re trying to upgrade everything, but we can’t accomplish that overnight.  The installed system reliably creates and detects hook flash.  No doubt the reason it works more reliably here is that nearly every implementation (probably ALL implementations, but I don’t know that for certain), uses a computer to generate the hook flash.  It’s not a user depressing the physical switch on a black phone.  Used to be, isn’t any more.  There isn’t any way to use some alternate signaling: the interface is CAMA, and that’s it.  At one point there was a push to upgrade these systems to use ISDN, but that got no where.  I’m not sure there are any existing systems that use ISDN.  They all use CAMA.  There are at least 4 brands of gateways that successfully do the right thing.   

Brian

> On Jun 9, 2016, at 1:59 PM, Cullen Jennings (fluffy) <fluffy@cisco.com> wrote:
> 
> 
> 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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> 

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