A method and apparatus for handling incoming service requests, where an application server comprises a set of traffic modules, each being capable of handling at least one predetermined multimedia service. When an initial service request is received from a requester, a load balancing function, capable of selecting basically any traffic module in the set of traffic modules, is applied to assign a traffic module in the set of traffic modules for handling the received service request. After processing the request, a response is sent to the requester including a port number associated with the assigned traffic module. When receiving a subsequent service request including a port number indication, a port mapping function is applied to determine the earlier-assigned traffic module associated with the given port number indication, for handling said subsequent service request.