1. A method in a node of a SIP domain for handling an incoming request for a SIP service at the SIP domain for which a user database query has failed, the method comprising the following steps: determining if a DNS domain name of said request is registered as a shared domain, by checking configuration data, said configuration data comprising all DNS domains managed by an operator of said SIP domain, resolving said DNS domain name into a globally routable URI, and one of routing said request towards a terminating entity if said DNS domain name is registered as a shared domain, and rejecting said request if said DNS domain is not registered as a shared domain.