Systems and methods for interoperability are disclosed which allow for a user of one network to communicate seamlessly with a user of another network. Users are provided seamless access to data services in different networks without having to subscribe to those networks. In one embodiment an application bridge comprising an application server may be used to service communications while a billing bridge may be provided to control and charge network subscribers. In one embodiment a user in a SMS domain may communicate with a user in an IP domain. In one embodiment, a platform may register with a federated interface of an IM domain to enable non-IM users to communicate with IM users.