For some reason we've had a fax service trying to deliver a fax via our voice # for the last two days.

It's probably some commercial spam or something, but it appears to be trying until it delivers, and I'd like to just let it go through.

Is there a way to transfer the call to a 'softmodem' in the system, or even hook up a fax modem on an extension to forward the call to?

This is with a CIX100 and LVMU VM card..

hook up a fax machine on an analog port and send the call to it.

Pretty much the only way to recieve a fax is to connect a fax machine, as mentioned. If you don't have an analog port on the system, you can try to forward the call to your fax machine.

As long as you can transfer calls externally, just transfer the call to your fax number, by pressing the transfer key, pressing 9, then dialing the fax number and disconnecting.

I agree with both Voyager and newtecky. Connect a fax and transfer or direct the call to it.

On another note... Have you tried faxing the number back, with a note saying "You are trying to fax our main voice line, please remove XXX-NNNN from your system"?