Fax machines typically use a RJ11 or regular phone line for connecting. This connection that then needs to go to a RJ45 Ethernet connection (RJ11 TO RJ45). When you want to integrate an existing fax machine to an IP-PBX you will need to convert the analog fax line to an Ethernet or RJ45 connection. One way to do this is to use an ATA (Analog Telephone Adapter) such as, a Cisco SPA122, SPA112 ATA, or a Cisco/Linksys PAP2T which will accept an analog RJ11 phone connection from the fax machine using one of the Phone Port connections (Line 1 or Line 2).
You would typically mount the SPA112 or SPA122 in the phone closet near the Asterisk server using the RJ11 phone line already in place back to the fax machine. The Ethernet connection would connect into the switch connecting back to the Asterisk server as an extension.
After connecting up the ATA as the analog gateway device and making sure that adequate bandwidth exists, you may want to take advantage of some of the configuration changes that will help ensure the best possible result when faxing. *Ensure that your device is running the latest firmware.
<FAX_Tone_Detect_Mode_1_>caller or callee</FAX_Tone_Detect_Mode_1_>