Fusion Connect Blog

What Devices Still Rely on Your Old Phone Lines (POTS)?

Written by Fusion Connect | January 27, 2026 9:00:00 AM Z

You may have replaced desk phones years ago—but that doesn’t mean copper phone lines are gone. In many buildings, they’re quietly supporting systems you don’t think about until something breaks.

Common Devices That Still Use POTS

Before disconnecting old lines, check for:

  • Fire alarm panels
  • Elevator emergency phones
  • Security and door access systems
  • HVAC monitoring and control systems
  • Fax machines or legacy payment terminals

These devices often sit outside the IT spotlight—but they’re compliance-critical.

Step 1:
Inventory What’s Connected

Start with your demarc or phone bill:

  • Identify every active copper line
  • Trace where each line physically runs
  • Confirm what device it serves

If a line doesn’t have a clear owner, that’s a red flag.🚩

Step 2:
Confirm Replacement Compatibility

Modern POTS replacement solutions can support many—but not all—legacy devices.
Verify:

  • Power requirements
  • Battery backup expectations
  • Signaling or supervision needs

Assumptions here can lead to compliance gaps.

Step 3:
Test Before You Cut Over

Once replacements are installed:

  • Test alarms, elevators, and emergency systems
  • Confirm monitoring centers receive signals correctly
  • Validate failover and battery behavior

This step matters more than the install itself.

Step 4:
Document Everything

Post-install, make sure you have:

  • Updated compliance documentation
  • Test results on file
  • Clear ownership for ongoing monitoring

This protects both IT and facilities teams down the line.

The Bottom Line

For many organizations, the hardest part of POTS replacement isn’t the technology—it’s knowing what’s safe to disconnect and what absolutely isn’t. Legacy devices don’t always announce themselves, and missing one can create compliance or safety risks.

Fusion Connect helps businesses inventory legacy lines, validate replacement options, and confirm post-install compliance. So critical systems like fire panels, elevators, and access controls continue to work exactly as intended.

When it comes down to it, POTS lines don’t disappear on their own—and disconnecting them without verification can create real risk. A careful audit, proper replacement, and thorough testing help ensure nothing critical gets left behind.