Abstract: Each of a plurality of data items has an associated update time. Identifying updated data items comprises identifying those data items that have an update time later than a last synchronization time. The data items are updated such that each data item is associated with one of a plurality of update tokens. Each update token is associated with updates performed up to a respective bound period from a time at which the update token is superseded by a successive update token. The update tokens are allocated successively in a monotonic sequence. Data indicating a last synchronization time is received. An update token is identified that is associated with one or more updates performed relative to a point in time related to the last synchronization time by the bound period. Data items having an update time after the last synchronization time are identified on the basis of the identified update token.

Abstract: Measures for operating a user device in a telecommunications network. In a browser on the user device, a password associated with a given telephony service identifier is stored in a browser cache associated with the browser. A user of the user device has one or more telephony service identifiers, including the given telephony service identifier, allocated by a service provider for conducting communication services in the network. In the browser on the user device, in response to receipt of user input via the browser indicative of a request to conduct communications using the given telephony service identifier, the stored password is retrieved from the browser cache and used to authenticate the user device for at least one communication service in the network using the given telephony service identifier.

Abstract: Each of a plurality of data items has an associated update time. Identifying updated data items comprises identifying those data items that have an update time later than a last synchronization time. The data items are updated such that each data item is associated with one of a plurality of update tokens. Each update token is associated with updates performed up to a respective bound period from a time at which the update token is superseded by a successive update token. The update tokens are allocated successively in a monotonic sequence. Data indicating a last synchronization time is received. An update token is identified that is associated with one or more updates performed relative to a point in time related to the last synchronization time by the bound period. Data items having an update time after the last synchronization time are identified on the basis of the identified update token.