This is taken directly from the Network Alchemy FAQ Section:
Question:
How can I configure DDI to DTMF for use with fax servers?
Answer:
Individuals or departments can now have their own fax number. We pass the information to the fax server, which could only have one or two lines, as DTMF tones which identify the individual.
Configuration Example:
The Fax modem is on extension 216, set this extension for Caller Display Type = DTMFB. Configure a HuntGroup extension 500 with 216 as a member. Now Configure a User Fax501 on extension 501 and set Forwarding Unconditional to 500. Finally set an incoming call route of a personal fax number of 699001 to 501.
Repeat for 502 etc...