Generic Access Network (GAN) allows cell phone data to be transmitted over Wi-Fi networks rather than cellular networks. A GAN Controller receives data from the internet and routes it into the phone network. GAN is commonly used to implement Wi-Fi Calling, allowing mobile phones to make calls over Wi-Fi like they would over cellular networks. GAN provides advantages for both carriers by increasing coverage cheaply, and subscribers by allowing cellular service wherever Wi-Fi is available and avoiding international roaming charges. However, subscribers need a GAN-compatible phone and calls may be disrupted during handoffs between Wi-Fi and cellular.