Ability of a mobile user to access cellular services while away from the home network. This includes automated roaming between GSM networks, SIM-based roaming, where a user switches the SIM card into a mobile phone from a different network, or roaming across technologies (for example, between a WCDMA network and the GSM network of another operator). Roaming can take place within one country and across national boundaries. In a WLAN context, roaming occurs when a mobile device disassociates from one access point and then re-associates with a new access point.