How to find the right Modem Cables AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Modem Cables
- Line cord type
- Dial-up, fax and DSL lines use RJ11 phone cords. Ethernet uses the wider RJ45 connector. An RJ11 plug in an RJ45 jack connects loosely and can damage the outer pins.
- Conductor count
- A single line needs 2 conductors. Use a 4-conductor cord for two-line jacks. Two-line devices need the second pair of wires.
- Serial modem wiring
- External serial modems need a straight-through DB9 or DB25 cable, not a null-modem cable. A null-modem cable swaps the transmit and receive lines, so the modem will not respond.
- DSL filtering
- Put a DSL filter on every phone and fax that shares the line, but not on the DSL modem itself. Unfiltered phones cause line noise and dropouts on the DSL connection.
Brands that matter
- Cable Matters: Basic RJ11 and serial cables.
- StarTech: DB9 and DB25 straight-through modem cables.
- Tripp Lite: Serial and telephone cabling.
- Monoprice: Inexpensive phone line cords.
What to avoid
- Null-modem cables for connecting an external modem.
- Forcing an RJ11 plug into an RJ45 Ethernet port.