[VoIP] Seattle Museum?

[Steph Kerman]

That certainly makes sense but why then do I hear DTMF for the duration 
of my keypress when doing end-end signaling?  Apparently the cellphone 
itself is (also?) generating DTMF.

OTOH, people have used acoustically coupled DTMF tone generators with 
considerable success for years.  Considering the high inherent 
distortion level of the typical carbon transmitter and low distortion 
component receiver tolerance specs required for rejecting digits to 
prevent talk-off, that ought to work far less reliably than it does.

Steph

Donald Froula wrote:
> On modern cell networks, the DTMF key press is converted to a message 
> and sent over-the-air to the base station/network where the DTMF is 
> regnerated at a fixed length, decided by your provider. Most of the 
> codecs in use these days don't work too well for in-band tones. 
> Although, I can whistle off my
> ProjectMF server with 2600 HZ over a good cell connection!
>
> Don
>
> --- Steph Kerman <stfkerman at jps.net> wrote:
>
>> I've generally found that John Covert's portal works
>> well, well enough 
>> that I can even store the CNET number on a speed
>> dial key and dial it 
>> into CNET over his voice prompt or over the
>> modulated dial tone.  I do 
>> this after first dialing the PSTN access number for
>> the portal itself 
>> from another speed dial key. 
>>
>> I am also able to do this from my cellphone.  In the
>> case of the 
>> cellphone, the DTMF is passing over the cellular
>> network first.  
>> Amazingly, it works.
>>
>> Steph
>