How can I fax with Mac OS X?

March 5, 2006 10:01 PM

Why am I having such difficulty sending a fax via my Mac OS X computer? There is well-advertised built-in fax functionality via CMD-P. I can receive faxes just fine in this fashion, but cannot successfully send. Could it be because my 'phone' line is actually VOIP (Vonage)? Must be overlooking the obvious here.
posted by jeffmacintyre to computers & internet (8 comments total)

Probably. You need to activate fax service on Vonage residential lines. There is a one-time cost for this. Once activated, you may also have to lower the baud rate on your faxmodem.
posted by danhon at 11:07 PM on March 5, 2006

I'm surprised you can even receive via Vonage. A regular Vonage line isn't the same as a standard copper pair; instead, it's digitizing your voice and sending a VOIP stream. That digitization process throws away a lot of the information that faxes use, so they normally don't come through. Perhaps it throws away less data on an incoming call from a copper line??

What you can do, though, is get a dedicated fax line from them. It uses the second port on your phone device. The fax line uses a different codec that works only with faxes, so you can't use it for voice. It doesn't support a regular modem either, much to my chagrin... I wanted to use my Vonage line to call some old BBSes that are still around, and couldn't.

But it does work splendidly for faxes.
posted by Malor at 11:54 PM on March 5, 2006

I have received and sent faxes from a PowerBook using both Panther and Tiger via Vonage. I do remember once having trouble sending. I don't recall having to activate anything special with Vonage. Are you sure all your Fax settings are correct?
posted by anathema at 3:03 AM on March 6, 2006

I don't have any experience with Vonage, or even directly with VoIP, but I used to be in the Telephone Via Weird Digital Technology business, and I can confirm that these technologies will usually indeed mangle fax.

The digitization of the audio signal (i.e. quantization, sampling, compression, etc.) is designed for voice, which means it's doing just barely enough to maintain quality just so humans won't notice the difference. But the fax machines most certainly do notice, to the point of not syncing at all. So in most of these systems they implement something called "fax relay" (at least that's what we called it) which takes the fax audio signal, converts it back to actual binary data, transmits that via the data connection, reconverts it back to fax audio signal at the far end, and then spits that audio out to the fax machine at the other end. It's a horribly kludged system that fails routinely, especially when you start getting latency on the circuit, such as might be introduced be, oh, a clogged internet pipe. In my case it was satellite hops that made it suck (250 ms latency on each hop).

Anyway, that's not really addressing your problem, it's just background!
posted by intermod at 4:49 AM on March 6, 2006

I can't add anything helpful about faxing from Mac OS, but I do have Vonage and send and receive faxes just fine without a dedicated fax line and without having to activate anything special.
posted by phox at 4:52 AM on March 6, 2006

As yet another data point, I can't reliably send/receive faxes with Vonage. They routinely drop after a few pages.

I switched to eFax.
posted by I Love Tacos at 5:52 AM on March 6, 2006

The main key that I found to enable faxing via Vonage was to turn off V.42 error correction. If that was on, there was about a 50-50 chance of being able to fax any given page. If it's off, faxing worked fine.

V.42 just assumes a line of a higher quality than Vonage is able to provide.
posted by jellicle at 5:55 AM on March 6, 2006

Try dialing *99 before the phone number.
posted by kindall at 10:40 AM on March 6, 2006