Roaming

Roaming services are usually provided by cellular service providers as well as Internet service providers (ISP) via a cooperative agreement. Traditional cellular roaming services are provided by both the Global System for Mobile Communications (GSM) and code division multiple access (CDMA) operators. Services are either free or billed according to local area rates. Wireless telecommunication roaming services are usually included in mobile/cellphone subscriber service packages for use outside local networking zones.

GSM/WLAN roaming services can be supplied in two different scenarios. One is SIM-based roaming and the second is username/password base roaming.

Wireless local area network (WLAN) roaming services are segmented as follows:

• Internal Roaming: Implemented when a mobile station is transferred with a strong signal between access points, preventing network blockage or interruption from weak signals.
• External Roaming: Implemented when a mobile station shifts to a wireless LAN or other foreign Wireless Internet Service Provider (WISP) to access service. WISP allows users to maintain an Internet connection while moving within a local coverage area.

An ISP uses special software to automatically track roaming usage and corresponding billing. To benefit from roaming, subscribers should have an ISP connection that supports roaming. A traveling user may route calls to the ISP's locally assigned number after logging into a foreign ISP through a computer modem. The foreign ISP provides Internet access after validating the user's home mail server.