How can I simulate a modem over a VOIP connection?

I have a hardware device I need a server to dial into at regular intervals. The problem is I no longer have a POTS line or a modem in any of development computers, and all my production servers are virtual. I went out and got a usb modem for development and will plug it into a broadvoice VOIP line, but this seems quite kludgey. I've googled around and have found "virtual modems" that simulate serial connections or "at based" modems over IP, but so far nothing supports SIP or any kind of VOIP.

Is there a way to connect a virtual modem to a real one?

Thanks.

Update Putting a computer near the device isn't a good option as its in a public basement, (though the ALIX boards might work) and even then I'd have to dial into it. I also can't replace the modem with a serial device or an ip device as the only connection to location is the phone line and I don't know enough about the device to modify it. This is for some old smart meter equipment.

Solution 1:

To save your sanity, don't.

Modems (and fax) over VoIP are extremely sensitive to timing, and usually break over VoIP, it might even seem to work at first, but it's certain to break.

Adding virtual machines just makes the problem worse.

There are "short haul modems" around which can emulate a phone line.

Another option is just to attach the two modems back to back:

http://www.jagshouse.com/modem.html

Solution 2:

I have a similar need, and I've been searching for hours and hours for a solution. The closest I've found is a free but not very well-written program called "TimeFax" (http://sourceforge.net/projects/timefax/), which installs a virtual COM port and connects it to an H.323 receiver. You can make Windows install a legacy 14k modem on that COM port, and theoretically the program will take the COM port data and transform it to H.323 and pipe it to whichever receiver you specify. Then all you need is a VoIP H.323 termination, and you might be good.

Note that to get TimeFax working on Windows Vista or 7, you have to disable desktop composition in the compatibility settings. You'll also have to manually download the 2 dll files that it is missing, which it will complain about when you first try to run it. A quick Google search finds them easily though.

You'll still have issues with VoIP compression, but if you lower the speed, you might be able to achieve something that works. A few years ago I routed a dial-up modem through a Vonage connection, and it worked surprisingly well if I kept it at slow speeds (like 14k), so I know that dial-up over VoIP is possible, I just haven't quite got a completely software solution working.

Solution 3:

We use Cisco ATA 186's to on all of our faxes and as a backup in case our WAN goes down and we need to get into our networking gear at the Datacenter ... 1900 miles away. They've served us very well

EDIT:

In that case of purely software devices ... they don't exist. I tried looking high and low. Including trying to hack something together with asterisk ( with the help of an asterisk hacker i work with ). I was looking for a situation where i could dial into the modem on our network gear anywhere even when all I had was my Cell card.