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Re: Min DTMF Gap

From: Harald Alvestrand <harald@alvestrand.no>
Date: Fri, 17 Jan 2014 07:42:01 +0100
Message-ID: <52D8D0B9.9050606@alvestrand.no>
To: public-webrtc@w3.org
On 01/17/2014 01:43 AM, Roman Shpount wrote:
> I was the person who asked for this change.
> Based on http://www.itu.int/rec/T-REC-Q.24-198811-I/en Annex A, valid 
> tone duration is 40 ms and up. Valid gap duration is 30 ms (minimal 
> for Japan) and up to 70 ms minimum in Australia. So, my suggestion was 
> to keep defaults at their current values but allow to set minimal 
> values to minimal possible legal values (40 ms tone and 30 ms gap). My 
> justification is that DTMF is a legacy interop feature and it should 
> be able reproduce any legal DTMF string which can occur in the wild by 
> modifying the JavaScript parameters.
Current text:

The duration parameter indicates the duration in ms to use for each 
character passed in the tones parameters. The duration cannot be more 
than 6000 ms or less than 70 ms. The default duration is 100 ms for each 

The interToneGap parameter indicates the gap between tones. It/must/be 
at least 50 ms. The default value is 50 ms.

So you're suggesting that 70 ms change to 40 ms, and "at least 50 ms" 
change to "at least 30 ms"?

I don't have a problem with that - I think it's risky for an app to use 
bursts so short that they are not required to be detected in some 
jurisdictions .... but that's the app's problem, not mine.

> _____________
> Roman Shpount
> On Thu, Jan 16, 2014 at 7:19 PM, Cullen Jennings (fluffy) 
> <fluffy@cisco.com <mailto:fluffy@cisco.com>> wrote:
>     This has been sitting on the editors todo list for a long time and
>     I wanted to try and sort it out 
>     The gap between DTMF digits is currently specified at 50ms. Long
>     ago someone requested we change this to 40 ms.
>     Does anyone remember why people wanted to make this change?
>     Thought on if it should be 40 or 50?
>     Thanks, Cullen
Received on Friday, 17 January 2014 06:42:32 UTC

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