Wireless data services such as wireless email are becoming common, and in particular, “always-on” systems, where new email is automatically forwarded by the service provider to the wireless device. The problem is that there is no effective mechanism for implementing “always-on” systems when the user is moving around a network, or from one network to another. The invention addresses this problem by generating a session key at the service provider's system for a given data session, and returning this session key to the mobile device. Each time the mobile device communicates with the service provider, it enters this session key into a field that will simply pass through the communication network to the service provider. This allows the service provider to manage the data session, preparing proper accounting records and directing the deletion of stale data sessions on network resources.