Sharp MX-C557F User Manual page 58

Faxing
Connecting the printer to a non‑RJ11 wall jack
1
Connect one end of the telephone cable to the line port of the printer.
2
Connect the other end of the cable to the RJ11 adapter, and then connect the adapter to the wall jack.
3
If you want to connect another device with a non‑RJ11 connector to the same wall jack, then connect it
directly to the telephone adapter.
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