ZyXEL Elite 2864 User Guide - Page 171

The following flow control signaling is used while receiving a fax: CTS is not used when receiving a fax. RTS is used to inform the modem that the computer cannot accept data at this moment. The modem will not pass received data to the DTE if RTS is turned off. When finished receiving the fax message, the modem will turn off CD, then send a status report result code to the DTE. Parallel Receiving with the Fax Machine You can connect the modem and a fax machine on the same line and have the modem answer data calls and the fax machine answer fax calls, respectively. The modem will distinguish a data call from a fax call and make the switch. The setup procedure follows. 1) Plug the phone cable from the wall jack into the modem's Line Jack. 2) Plug the phone cable from the fax machine into the modem's Phone Jack. 3) Turn on the DTE and set S38b4 to 1 by sending ATS38.4=1 to the modem. This will disable the modem from receiving a fax. 4) Set the modem auto-answer ring number to be the same as your fax machine's setting. For example, if you have set your fax machine to answer an incoming call after 2 rings, then you need to set the modem to the same ring number by sending the command ATS0=2 to the modem. Now, when a call comes in, both the modem and the fax machine will go off-hook after the same number of rings. However, the line is initially connected to the modem and cut off from the fax machine when the modem goes off-hook. The modem will try to handshake on the incoming call. If it is a data call, the handshake will be successful and a connection will be made. The fax machine being cut off from the line will fail the handshake and go on-hook after a time-out. If, during the handshake, the modem finds that it is a fax call , it will disconnect since bit 4 of S-register S38 is set and the fax machine will get the line. The fax machine will handshake successfully in this case. Fax reception from within a BBS System ZyXEL modems have the feature of automatic detection of data and fax calls, and allow a BBS software to receive faxes on the same phone line. To make your BBS receive the incoming fax, you need to do the following setup change in your BBS: 1) Add the string #B1+FCLASS=6 to the init string. Be sure the +FCLASS=6 command is the last command. 15-17