[cptnbob]

One of our clients still has a DOS box connected to a 14.4k modem that we have to drag EDI interchanges off. You wouldn't believe how much it cost to get a modem and POTS line installed in our DC so we could talk to it. There's a windows service written in .net that talks to it via a serial port and POSTs it to a REST endpoint.

[cnvogel]

Of course you could put a small internet connected embedded box to your clients place... (maybe even a commercial terminal server, if you trust the security of it) and directly emulate the whole modem+POTS line.

[cptnbob]

They paid for our modem setup so meh ;-)