The smallest type of cellular base station.

A femtocell contains technology similar to a standard base station (commonly called a tower) but scaled down to something the size of a large book. Femtocells are smaller than microcells and picocells. The area of coverage provided by a femtocell is similarly small.

While others types of base stations are professionally installed by the carrier, a femtocell is designed to be installed by the end user.

Femtocell technology competes in many ways with UMA technology. Both allow end users to "create" coverage in their own homes and offices by simply purchasing and setting up a small piece of equipment at that location. While UMA uses Wi-Fi or Bluetooth as the local wireless link and requires a special UMA phone, femtocell technology uses standard cellular wireless technology (such as GSM or CDMA) and thus does not require a special phone.