The PLMN- specific parameters can handle the following operations: the transferrence of subscriber data when updating the subscriber data fails; the defining of denied services and roaming limitations (i.e. not allowed basic or supplementary services and roaming not allowed for a subscriber with a certain service). Core Network Planning and Optimisation With these parameters the operator can define whether a subscriber with a certain service set is allowed/not allowed to roam in a given PLMN or whether the subscriber is removed from the VLR when the location update fails, as well as the supported CAMEL phase. It is important that these parameters are the same in all MSSs of the network. Naming and Numbering Analysis The network naming convention should be studied to ensure naming consistency within the network. Inconsistent naming of NSS elements and components makes the work of network analysis and mainte- nance very difficult. It should therefore be avoided where possible. A proper naming convention should be agreed with the operator and implemented consistently in all network elements. Naming of CS Core Network Elements The naming convention applied in the network should be examined for uniformity and consistency in the network. The operator should make maximum use of the available possibility for naming of MSCs, HLRs, VLRs, PABXs, POI (other networks), prepaid nodes, etc. Circuit Group Naming Conventions The operator should also make maximum use of the available possibility for naming the circuit group. For example, the naming of the circuit group to the Helsinki MSC could be MS1HE01B, which means that it is a circuit group to MSC in zone 1 (or G for the GSM network) located in Helsinki and it is the first MSC and is a bidirectional circuit group. Circuit group numbering should also be harmonised in the network and should present a consequent reasoning and consistency. Naming of Destinations The destination name should identify the destination MSC, network element or POI to which the traffic is routed in the 