Re: Comcast Telephone Service????

[Nomen Nescio <nobody@xxxxxxxxx>]

Bass said:

>Almost every ATA device's CODEC can handle DTMF (touch-tine) signalling.
>Becaue some alarm transmission formats employ DTMF, these
>may be better suited for use with VoIP service than others, especially
>pulse formats.  NBo guarranty here that some particular unit
>will work.  You just have to experiment.

Thanks for the info on silence suppression and echo cancellation.  Do you
know whether these settings can be controlled by user programming, or
whether the VOIP provider has to do it?  The information I read said that
these two settings often cause problems for fax machines and modems trying
to transmit over VOIP.  Presumably, that also includes alarm panels that
use modem formats.

Although codecs seem to be designed to handle DTMF signalling, that is
apparently a different issue than end-to-end DTMF transmission.  From what
I gather, the basic 8 bit codec can handle DTMF signals from a touch-tone
phone, but those digits are converted into digital data and sent out as
part of the signalling protocol.  By contrast, a DTMF device like a Contact
ID dialer wants to dial the number (supposedly, not a problem for VOIP) and
then transmit touch-tones end-to-end (which seems to be a problem for the 8
bit codecs).  If true, this should be indicated at the digital receiver by
transmission errors, rather than a failure to connect at all.  I don't know
whether codecs are even designed to support pulse dialing; I suspect not.

I am the first to admit my knowledge of this subject is extremely limited,
so I encourage anyone with good VOIP technical knowledge to correct and
elaborate.

- badenov