In a mobile communication system, receiving changed information for a service of interest in a next modification period comprises determining in a current modification period whether an alarm bit whose assertion indicates upcoming changed information is unambiguously associated with the service of interest or whether the alarm bit is associated with the service of interest and one or more services that are not of interest. Mappings of all services to alarm bits are analyzed in the present and possibly in one or more upcoming frames during the current modification period and applied in embodiments to reduce the ambiguity and therefore the risk of false indications of changed data for the service of interest.