Instead of rejecting an incoming request at a node of a SIP domain, e.g. an IMS domain, when a user database query has failed, it is determined whether the DNS domain name of the request is registered as a shared domain or not. If it is found that the DNS domain name is registered as a shared domain, the DNS domain name is resolved into a globally routable URI, and the request is routed towards the terminating entity. If, however, the DNS domain name is not shared, the request is rejected. Such a mechanism enables operators to allow for a DNS domain name to be utilized by more than one SIP domain.