What is a POTS line?
POTS stands for "plain old telephone service": the analog phone line that runs over copper wire from the phone company to your building. Most businesses still have a few, often without knowing what they are connected to.
Updated October 15, 2026 · Twisted VoIP
POTS in plain terms
A POTS line is a pair of copper wires that carries an analog signal and its own small electric current from the phone company's central office to your building. That current is why an old landline phone kept working in a power outage, and why alarm panels and elevator phones were built around these lines.
Phone companies also call these lines "1FB" (one-party business line), "B1" or simply business lines. Your bill may list them as local lines, measured business lines or by a 10-digit number with no description.
What businesses still use them for
- Fire alarm panels that dial the monitoring center (usually two lines)
- Burglar alarms and security panels
- Elevator emergency phones
- Fax machines
- Gate entry systems and call boxes
- Older card terminals, ATMs and postage meters
- Main phone numbers and older phone systems
The lines that cause trouble are the ones nobody thinks about: a fire panel line in a closet or an elevator phone that has been dialing out over the same copper pair for twenty years.
Why POTS lines are going away
Phone companies are retiring their copper networks and moving customers to fiber, cable, wireless or internet-based service. To stop offering copper phone service in an area they file with the FCC, and those filings now cover thousands of telephone exchanges. See the timeline of filings or check your own line.
Even where no filing has been made yet, copper lines keep getting more expensive. Many businesses pay $80 to $150 or more a month for each one.
How to find the POTS lines you have
- Go through every phone bill, line by line. List each 10-digit number.
- For each number, find what it is connected to. Call it and listen: a fax tone, silence or an alarm panel picking up all tell you something.
- Ask your alarm monitoring company which numbers your panel uses, and your elevator company which number each elevator phone dials from.
- Look for lines nobody can account for. Those are often ones you can cancel.
What replaces a POTS line
| Line used for | Usual replacement |
|---|---|
| Main business phones | A cloud phone system (business VoIP); you keep your numbers |
| Fax | Online fax, or a cellular line replacement |
| Fire alarm, burglar alarm | A cellular communicator or a cellular line replacement such as Ooma AirDial, approved by your fire marshal |
| Elevator phone | A cellular line replacement built for elevator use |
| Gate, call box, card terminal | A cellular line replacement, or the equipment maker's own internet or cellular option |
See the POTS replacement comparison for how the main cellular replacements differ.
Is your line on a filing?
Questions
Is a POTS line the same as a landline?
Mostly. A traditional landline is a POTS line. Some services sold as "home phone" or "business phone" today run over cable, fiber or the internet instead of copper, so they look like landlines but are not POTS.
Do POTS lines work in a power outage?
A copper POTS line carries its own power from the phone company, so a simple phone on it keeps working when the building loses power. Replacements use batteries instead, so battery runtime matters for alarm and elevator lines.
Can I keep my phone number when the POTS line is replaced?
For phone and fax lines, usually yes: the number is moved (ported) to the new service. Alarm and elevator lines often do not need their old number, but check with the monitoring or elevator company first.
Get a plan for your lines
Tell us what runs on your copper lines. We'll check the filings for your address and tell you what we'd replace each line with. No obligation. Prefer to talk? Call 623-307-5548.
Related guides
General information, not legal or code advice. Requirements depend on your state, your local authority and your equipment.