What kind of fax modem does ExtraFax support?

Link:  http://www.extracomm.com/Extracomm/FAQ.NSF/FAQs/41d59b1b495f0f4785256b6400753fc2
Apply to:  ExtraFax for Exchange; ExtraFax for Domino All versions

Last Modified Date:  10/10/2013

ExtraFax supports most of the fax modems, internal or external. (Except software modems)
1) Class 1 Generic fax modems
2) Class 2 Generic fax modems (Strongly recommended; most reliable amongst the three supported fax classes)
3) Class 2.0 Generic fax modems

Normally, the default setup-string for the fax modem works for most of the common modems. However, different brands or models have different behaviour.

To check whether the fax modem supports protocols other than Class 1, you may open a terminal program and type the following commands to the modem's com port:
AT <enter>
AT+FCLASS=? <enter>
The modem should return OK for the first command and something like 0, 1, 2 for second line to indicate which protocol(s) it supports.

In case you need to use a different setup string, please consult your modem manual or the modem vendor for proper setup-string of the modem.