802.11u

802.11u is an amendment to the IEEE 802.11 WLAN standards that provides for connection to external networks using common wireless devices such as smartphones and tablet PCs.

An 802.11u-capable device can take advantage of Hot Spot 2.0, also called Wi-Fi Certified Passpoint, designed for public-access Wi-Fi. Hot Spot 2.0 enables cellular-like roaming among Wi-Fi networks and between Wi-Fi and cellular networks. If a subscriber is in range of at least one Wi-Fi network, the device will automatically select a network and connect to it. Other benefits include an enhanced data transfer rate (DTR), and service on demand. 

Other notable features of 802.11u include the transmission of pre-connection information to prospective users defining the type of network offered (private, free public, chargeable public, emergency, etc.) as well as the venue type (educational, residential, business, vehicular, etc.); roaming consortium information; the ability to receive messages from the Emergency Alert System (EAS); and the ability to contact emergency services when necessary. Network discovery and selection is facilitated by the Access Network Query Protocol (ANQP), which comprises elements defining the services offered by an access point.