All;
I'm trying to work up a solution for a potential customer and I came across a possible deal breaker.
They have 2 credit card terminals in 2 different locations. At first I was thinking that I could simply use an ATA for each device, but then I came across this statement:
"Visa & MasterCard officially state there is no acceptable VoIP solution that meets PCI Compliance requirements." http://3dmerchant.com/blog/2008/12/21/voip-credit-card-processing. It boils down to credit card data flowing in unencrypted packets over the internet.
A probable and less than ideal solution would be that they need to keep a couple POTS lines in each location. Anyway, I thought this was interesting. I'm glad that I came across this now, rather than at installation time.
FSD
It a question of speed and echo cancellation
I use voip for credit card terminals all the time. Here's the deal with them:
First, you need a good ATA that will kill echo supression and cancellation completely, like any Linksys ATA.
Second, on that ATA, go to the line make Silence Supp Enable: no, Echo Canc Enable: no, Echo Canc Adapt Enable: no, Echo Supp Enable: no. You must use g711 codec, otherwise it will not work. Like eeman said, t.38, cisco fax forwarding, etc has no bearing because no fax handshake.
If the credit card modem is slow, like under 14.4K bps, the codecs can handle it and it will work everytime. If it is faster than that, the codecs have more difficulty carrying the tone as the speed increases to v.90 /56K, which is a miracle if it somehow works, though I did see it one time.
assume the same thing for Alarm panels. never try to voip an alarm panel or other modem devices; there is no such thing as a t.38 solution for modems and alarms. When obtaining new clients who use CC machines, the first question that should pop into your head is 'are they using pots lines or is it an Ethernet machine connecting up to a server somewhere'. Most corporate retailers of larger scale POS machines will be on ethernet back to a server and wont need a POTS line. Smaller stores that use the stand-alone machines with a analog line plugged into it will need to keep a traditional 1FB.