Lotus Sametime Unified Telephony, as a VoIP switching system, can be used to create a virtual voice network (a voice VPN) on top of the enterprise's existing data network topology for connecting subscribers within the enterprise, even if these subscribers are in different locations.
In addition to subscribers directly registered on the Lotus Sametime Unified Telephony system, this voice VPN can also include subscribers on traditional PBX (Private Branch eXchange) which are connected to the Lotus Sametime Unified Telephony through a gateway.
Lotus Sametime Unified Voice's sophisticated dialed number processing permits the administrator to create a PNP (Private Numbering Plan) which can include all subscribers in the VPN. Lotus Sametime Unified Telephony can serve as a tandem switch/routing engine in the VPN, connecting parties on the various PBXs, while at the same time serving directly registered endpoints.
Parent topic: Numbering Plan