Roaming enables a mobile subscriber to automatically make and receive voice calls, send and receive data, or access other services when travelling outside the geographical coverage area of their home network, by means of using a visited network.
Roaming is technically supported by mobility management, authentication and billing procedures. Establishing roaming between network operators is based on – and the commercial terms are contained in – dedicated roaming agreements.
If the visited network is in the same country as the home network, this is known as national roaming. If the visited network is outside the home country, this is known as international roaming.
If the visited network operates on a different technical standard than the home network, this is known as inter-standard roaming.
GSM Roaming, which involves roaming between GSM networks, offers the mobile subscriber the convenience of being able to use a single number, a single bill and a single phone in up to 219 countries. The convenience of GSM Roaming has been a key driver behind the global success of the GSM Platform.
The GSMA’s GSM Coverage Maps are a unique resource containing information supplied and approved by the members of the Association. The network, services and roaming information are continually updated to reflect the evolving situation worldwide. Interactive coverage maps, updated quarterly, allow you to navigate to see where exactly you can use your phone.
Please note, this page provides a high-level overview of roaming and does not indicate the full scope of roaming-related activities within the GSMA.
SMS and Data Roaming Explained Document (802kb, pdf)