Abstract: A method enables de-provisioning of subscribers and rerouting of an MMS, using the responses of external systems in the normal message flow of sending a MMS from the original network to an out-ported subscriber. There is automatic maintenance of subscriber records in communication networks such as GSM mobile networks. The automatic performance is achieved by monitoring network signalling messages, processing them, and implementing subscriber database processing modifications. The method comprises the step of a data management system receiving information from signalling flows and automatically acting upon this information to modify subscriber data in a database. The information preferably concerns message delivery operations and includes a HLR or HSS response to a routing request.