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Can I set telephone line as point to point lan network through dialup modem without internet conection?

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Short answer: yes — two analog modems can form a true point‑to‑point link over the telephone network so the machines talk to each other without Internet. That link behaves like a tiny WAN (PPP/SLIP) rather than Ethernet, so throughput is limited and latency higher than modern local networks. ’s note about speed is correct, and ’s point about declining vendor support explains why this is now a legacy solution.

Minimal checklist and setup notes: two working dial‑up modems and dialable phone numbers (or a line simulator that provides ring voltage), one modem set to answer and the other to originate; the answering side must accept incoming PPP sessions (Windows: Incoming Connections; Linux: pppd). Typical modem housekeeping commands that help are ATZ (reset/identify) and ATS0=1 (auto‑answer after one ring). Assign a small private IP range (for example 192.168.x.x) or let PPP assign addresses, enable file/printer sharing on the PPP interface, and ensure firewall rules allow the link.

Troubleshooting and gotchas: no dial tone or failed carrier usually means the voice line or ring signal is missing (many VoIP or business phone setups don’t pass modem tones). If the call fails during handshake, check modem standards (V.92/V.90) and turn off incompatible features; if authentication fails, confirm matching PPP auth (PAP/CHAP). If both machines are co‑located, a serial null‑modem, Ethernet crossover, or a tiny switch will be far simpler and much faster.

Practical caution: analog dial‑up is now legacy. Hardware, drivers, and support have become rare since the 2010s, so prefer Ethernet/Wi‑Fi or cellular/DSL links unless a specific legacy requirement mandates using modems.

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Member Avatar for JorgeM

Yes, if both computers have dial-up modems. This was very common many years ago. Keep in mind that the connection speed will be very slow compared to what we are use to these days.

Member Avatar for goatnetworking

This can be done, but companies like Cisco are discontinuing their support for dial up.

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