Two types of communication are generally supported: cordless/DECT/PCS protocols for short range or campus communications where all base stations are linked into the same LAN, and wider area communications using 3G/4G protocols. For example, voice over Wi-Fi offers potentially free service but is only available within the coverage area of a single Wi-Fi access point. Cordless protocols offer excellent voice support and even support base station handoff, but require all base stations to communicate on one LAN as the handoff protocol is generally not supported by carriers or most devices.