I am wondering what the notification e-mail looks like. Does it list the phone number that the fax was received from?
The trustfax notification email for a new fax will display the sending fax number (if available) as the last 10 digits of the file name. For example; the file name FAX_1878373_8019940800.pdf is from the sending fax number of 801-994-0800. The fax is attached as a pdf or tif file- you choose the format. PDF is the default format. The email notification can be sent to up to 10 email addresses.
There is also a text message notification that TrustFax can send to a cell phone. The text message has the file name with the last 10 digits as the sending fax and the date/time of the fax.
You can signup for a free trial account so that you can test the service at www.trustfax.com and click on signup.