A femtocell is a wireless access point that improves cellular reception inside a home or office building.
The device, which resembles a wireless router, essentially acts as a VoIP repeater. When
connected to Internet broadband, it broadcasts the connection using radio waves.
A cell phone call initiated in a home equipped with femtocall would start at the handset, be sent to the femtocell, go from the femtocell to the Internet through the broadband connection, and end up back on the cellular network.
Femtocells are compatible with CDMA2000,WiMAX, or UMTS mobile telephony devices, using the provider's own licensed spectrum to operate. One femtocell can potentially service up to five mobile devices concurrently.
Femtocells were originally called access point base stations. The term was derived from cell and "femto," a metric prefix that stands for 10^-15th, or one-quadrillionth, six orders of magnitude smaller than nano. The development of femtocells is credited, in part, to the work of a skunkworks team at Motorola in the UK, where they created the world's smallest full power UMTS base station.
Femtocell technology is still in its infancy, in terms of actual installations. Service providers are promoting the technology as a cost-effective way for customers to extend indoor coverage.