incoming tel call and fax call?
 

I am on Tmobile US network, I have the fax feature turned on couple years ago, which allows to receive fax on the cell number. Whenever people send me a fax to my cell number, it rings my phone as a regular call, if i picked i will hear the modem sound which try to communicate to the fax machine and of course the transmission will fail, if i don't pick up it will forward to my fax inbox by tmobile and i will receive the fax message alert just like voicemail message then i can forward it to a fax machine anytime i want.

Now my question is: is there anything difference between the incoming tel and fax call? if it is then i am sure it's possible to listen to dbus and alert me it's a incoming fax so i won't answer it, or even better to tell the n900 to ignore the call.