Out of range means a mobile phone cannot receive the radio waves from base stations, preventing calls and data communication. The screen displays "Out of Range" or "No Service." It occurs in mountains, tunnels, underground facilities, deep inside buildings, and at sea where signals physically cannot reach.
Three main causes exist. First, excessive distance from base stations. Second, signal blocking by concrete, steel frames, or terrain. Third, network congestion during major events or disasters when connections exceed base station capacity, creating effectively out-of-range conditions.
Calling a phone that is out of range plays a recorded message saying the phone is either out of range or switched off, with the exact wording varying by carrier. That is a pitfall: the message does not separate the two cases, so you cannot tell whether the other person deliberately switched the phone off or simply has no signal. Emergency calls (110/119) also fail in this state, so sharing plans beforehand is critical for activities in signal-poor areas like hiking or underground work.
Wi-Fi Calling enables calls over Wi-Fi when cellular signals are unavailable. Femtocells (small base stations) can improve home coverage. Carriers accept signal improvement requests for persistently poor coverage areas.
Where coverage is absent, the handset repeatedly scans for a base station, and where the signal is weak it also transmits at higher power each time it tries to register, so the battery drains faster than usual. Switching to airplane mode saves power when coverage is unlikely to return. If you subscribe to a network-side voicemail service, calls made while you were out of range are held as messages on the network and reach you once you are back in coverage.