A growing diffusion of LANs and development of more complex computer applications is pushing requirements on network providers for a new kind of service able to offer connectivity and performance comparable to that of LANs but over a metropolitan area or better inside a geographical extension. B-ISDN is the future answer that standardization bodies have identified and PTOs chosen; but availability of B-ISDN is foreseen only for the late 90s. In the meantime SMDS, elected as the first service in the context of B-ISDN, seems to be the right solution for current users' needs, especially for LAN interconnection. In order to provide SMDS early, evolutionary towards B-ISDN but realizable solutions have to be used: SIP has identified MANs as a technology to offer an SMDS-like service in the near and medium term, and to gather traffic for future B-ISDN in the long term. In this view SIP is experimenting with Metropolitan Area Networks (MANs) on field, together with other technology like star- based geographical networks.