 that are designed to improve cellular coverage in homes, small businesses, and outdoor areas. A femto- cell is a small device that plugs into the location's router SO that the mobile traffic is transmitted over the customer's wired broadband connection. The main benefit of femtocells is improved indoor coverage where it is not uncommon for thick walls or electromechanical interference to disrupt cellular signals. Femtocells can also be used as a low-cost way for mobile carriers to fill in outdoor coverage gaps where they can be installed on telephone poles. Femtocell gear within a customer's building consists of Access Points (APs) with integrated antennas. Technicians are not required to set up and install femtocells; they can be set up by the customer. The customer plugs the femtocell into a router, and then logs on to the Internet to identify the mobile phone numbers that are allowed to use the femtocell network. Setup at the carrier is highly automated. The access controller (gateway) located in the carrier's data center automatically configures the femtocell and sends the necessary billing information to the carrier's billing and maintenance system. This automated setup is referred to as zero touch provisioning. It is a key ingredi- ent in lowering the cost of adding coverage. In addition, the equipment itself is less costly than traditional, macrocell sites. Femtocells in Carrier Networks Femtocell traffic is routed within secure, encrypted software tunnels over a customer's broadband connections to a carrier's data centers. At the data center, femtocell traffic is routed by a gateway. The gateway removes the surrounding bits in the tunnel and sends the femtocell traffic to the carrier's core network. The gateway transmits traffic from thousands of femtocells either to the Internet or, for voice calls, to the mobile switch- ing center. Femtocell traffic bypasses base stations as well as the backhaul facilities that carry traffic to the core network. For mobile networks located in high-traffic metropolitan 