ZyXEL Communications Omni 288S User Manual page 52

Chapter 7 - Cellular Mode Operation
Some newer cellular models, particularly the hand-held ones, have an audio jack
that can connect the cellular phone's audio input/output to an outside headphone-
microphone set. A simple adapter cable can be used to connect the RJ11 modem's
2-wire interface to this cellular phone's audio jack. In this case, you need to
manually dial or answer a call using the cellular phone to establish a phone
connection and then manually make the modem go on-line using the ATD or ATA
command.
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