USB modem with Lion ?

It isn't compatible. Lion and Mountain Lion uses 64-bit, but it needs 32-bit kernel

Official statement from Apple:

http://support.apple.com/kb/ht3152

Look at the "More Like This" section to the left. That should solve your problem.

Sorry, you're right, it's on the right. I hope it's helpful.

I recently upgraded to mountain lion from snow leapard, skipping lion.

Apple's modem is supposedly not supported due to its need for a software driver.

However, I am able to use a Zoom USB Mini External modem Model 3095 with Mountain Lion.

No software driver required for the Zoom modem.

I just succesfully tried it with my new Macbook Air running Mountain Lion, OSX 10.8.2.

Of course you can also sign up for a fax by email service such as "My Fax" for around $10 per month to send and receive faxes through email.

Some of the more expensive fax/scanner/printers with fax capability may also support a fax modem through their own print drivers. Howerver, if you need to receive faxes, a dedicated analog telephone line may be needed. At $40 per month, the MyFax service is less.

Hope this helps.

You gain access to the zoom fax modem through the print to PDF command.