This paper describes usage of operator-independent Public user identities (PUI) for IP multimedia communication services for enterprises. This is a particular relevant topic for enterprises that wish to use their own domain name for public identification for (IMS based) communication services. Whereas usage of enterprises-specific domain names is common for services like mail and HTTP, it has some specific challenges for IMS based multimedia communication. These challenges include, among others: - uniform domain name for multimedia communication and other IP service, e.g. mail and http, without being tied to a single enterprise domain name administrator; - multi-IMS network subscription (within one country or across multiple countries); - non-country specific enterprise top level domain name (for example regional (e.g. .eu) or global (e.g. .com, .org) domain name); - real-time aspect of IMS services (as opposed to mail and http, which are not real-time).