FAX and POS terminal

Hello Luke,

FAX and POS (Point of Sale, EC-Cards-Reader?) its a very difficult thing with VoIP. Sure, the QoS in cable-plants with PacketCable and his dQoS with DSx-Messages are very good but for FAX is it recommend you use T.38 (Protokol for FAX over IP). I don't know if T.38 is usable with the POS and i believe not. The good news, POS with IP-Connectivity are still available.

We try FAX with the Thomson THG520 and THG540 until our Softswitch makes trouble. In the time, if T.38 works the transmit and receive of FAX was good! At my former work by a other Cable-ISP i know from issues with POS over POTS. At one time they will work and to other "more" time they have problems.

regards,

wittmann

P.S. Sorry for my poor english ;)

It's been a while since I've been involved in a VoIP launch, but on the hardware side I recall that echo cancellation had to be set to auto-detect on the media gateway. In that situation it is normally on for voice calls - but disabled for fax/data. The gateway would detect the fax/data tones and disable echo canx automatically.

Also, you need to be running pretty much error-free on the return RF carriers -- any significant loss (uncorrected FEC on the CMTS port incrementing) really destroys fax/data. At 0.1% uncorrected blocks, I'll start seeing calls about fax/pos machines failing. Hope that helps-