Abstract: The invention relates to a method for updating a wireless device connected to a cellular network utilizing Instant Messaging and Presence Service protocol (IMPS) defined by open Mobile Alliance. In the method a server connected to the cellular network transmits a configuration message to the wireless device including a CIDPrefix, which includes a provider specific identity string. The wireless device which has received the configuration message adds to the provider-specific identity string separation marks and a supplier-specific internal identity string. After that the wireless device uses this concatenated identity string as a ClientID with the server which sent the configuration message. The invention relates also to a configuration message, wireless device, server and device management system utilizing the method. The invention relates also to computer programs implementing the method in a server and a wireless device.