Switching from over-the-air cell towers to another form of transmission. Wi-Fi and femtocells are the two primary methods. For example, if Wi-Fi is enabled in a smartphone, it will use Wi-Fi for Internet access, although some phones can determine which service is less clogged at the moment and switch back and forth. Depending on the phone and carrier, voice calls can also be made over Wi-Fi (see
Wi-Fi calling).
Cellular carriers may also provide femtocells, which are mini cell towers inside a home or building that access the carrier's network via the customer's Internet service (cable, DSL, etc.). See
femtocell.