A user profile for use, for example in a personal numbering service, has an associated confidence value for each of the destination terminal numbers in the profile, a confidence value representing the confidence of a call being successfully answered at the associated network terminal. When a service using the profile needs to route a call for a user, the corresponding profile is accessed and the call is routed to the destination terminal number having the highest confidence value. The profile is managed to modify the confidence values depending upon the outcome of the call, and also upon registration of a personal number user at a network terminal. The confidence values are probabilities and when one confidence value is increased because of a successful outcome, the other values are adjusted. The confidence values can be a function of time to represent lessening confidence that a user is still at the network terminal of his last registration.