Clients (for instance, owners of ground equipment for satellite telecommunication network) are arbitrarily distributed on some territory. For maintenance/repair service, one uses Mobile Maintenance Stations (MMS) located at some Maintenance Bases (MB). The problem is to construct such maintenance zones which need minimum total number of MMS under condition that the Quality of Service (QoS) is not worse than required. A heuristic mathematical model of optimal zoning is suggested. An illustrative numerical example of constructing service zone for Florida State (USA) is given.