Short answer
A communication failure means the panel tried to send a signal to the monitoring company and could not get through. Until it is fixed, a real alarm may not reach anyone. The usual causes are a disconnected or VoIP phone line, a changed Wi-Fi or router, or an old 2G/3G cellular radio that no longer has a network. Call your monitoring company to confirm whether they are receiving signals.
On this page
What the message looks like
- Honeywell VISTA: FC on fixed-word keypads, COMM. FAILURE on alpha keypads.
- DSC PowerSeries: trouble 4 (failure to communicate) in the * 2 menu, often with trouble 3 (phone line). See DSC trouble codes.
- Touchscreen and app-based systems: a cellular, Wi-Fi, or "communication" trouble on screen, sometimes with a weak-signal indicator.
Cause 1: the phone line changed
Older panels dial the monitoring company over a landline. If you cancelled the landline, switched to fiber, cable, or VoIP phone service, or a technician rewired the phone jacks, the panel may have no dial tone or may not be able to send its tones reliably over VoIP. DSC panels add trouble 3 when the phone line is missing.
Fix: ask your monitoring company about a cellular or internet communicator. Most panels can take one as an add-on module, and many companies now require it.
Cause 2: the cellular network was retired
US carriers shut down their older networks: AT&T's 2G in 2017, and the 3G networks of AT&T, T-Mobile/Sprint, and Verizon during 2022. Any alarm still using a 2G or 3G radio lost its connection then. If your panel or communicator was installed before about 2018 and has not been upgraded, this is a likely cause.
Fix: the radio has to be replaced with an LTE model that suits your panel. Your monitoring company or the communicator manufacturer can tell you which one.
Cause 3: internet or Wi-Fi changes
Internet and Wi-Fi communicators lose their connection when you replace the router, change the Wi-Fi name or password, or the internet goes down. Reconnect the panel to the new network (touchscreen panels usually have a Wi-Fi menu) or ask your alarm company to help if it is a wired IP module.
Cause 4: account or signal problems
Sometimes the panel is connected but the monitoring account is suspended, the communicator's service plan lapsed, or the signal is weak where the panel is mounted. Your monitoring company can see the last signal they received and whether the communicator is still active.
What to ask your monitoring company
- When did you last receive a signal from my panel?
- Which path does my system use: phone line, cellular, internet, or more than one?
- Can we send a test signal now while you watch for it?
- If it is a cellular radio, is it LTE, and is the service plan active?
After any fix, always do a test with the monitoring company on the line. A clear keypad does not prove the signal is getting through.