Re: Any experience with Comcast digital voice for OOB (offlist is fine)

[Mark Tinka <mark.tinka () seacom mu>]

On Saturday, March 01, 2014 10:20:29 PM Eric Tykwinski 
wrote:

> I do remember though something about a modem over VoIP
> protocol being developed, something like Jay was saying
> about Faxing over VoIP, but I guess it never took off. 
> My guess being relying on the same line as an internet
> connection would be about that smart anyways.

FoIP (Fax over IP) is "dodgy" for a couple of key reasons:

        a) Different call capabilities, during setup, of SIP
           and T.30, where a portion of the segment is TDM.

        b) Different FoIP modes, during setup, where one end
           uses SIP and the other uses T.38, with an
           inability to propagate these capabilities across
           the circuit.

        c) Signaling delay between initial INVITE and 200
           OK, introduced due to SIP-SS7-SIP conversion.

        d) TDM-IP-TDM conversions causing incorrect training
           across the circuit.

        e) Low-rate codecs in the transit path that are not
           signaled to the end points, e.g., end points
           running at g.711 while an intermediate device
           runs at g.729.

My guess is modems would have the same issues.

In general, FoIP solutions have a better chance of working 
if a circuit provisioned to transmit a fax is all-IP (or, at 
the very least, limits the TDM-IP conversions). 

If all else fails, scan and e-mail.

Mark.

Attachment: signature.asc
Description: This is a digitally signed message part.