Public switched telephone network (PSTN) call scenario

The public switched telephone network (PSTN) is a standard, circuit-switched network that is optimized for real-time voice communication. When you place a call, you close a switch by dialing and establish a circuit with the other party. The PSTN guarantees quality of service (QoS) by dedicating the circuit to your call until you disconnect. Whether you and your connected party are talking or silent, you continue to use the same circuit until you disconnect.

In this scenario, numerous users within the organization are using applications that are compliant with H.323 Gatekeeper, such as NetMeeting 3.0 or later. H.323 Gatekeeper is installed and running on the network. Users register themselves with H.323 Gatekeeper using a well-known alias (such as an e-mail address) and a phone number. An H.323 gateway is also installed and running on the network. It is configured to enable H.323 Gatekeeper to direct calls between the IP and PSTN networks. All users are able to make calls to PSTN numbers by using NetMeeting to dial the number from their desktops. Users are also able to receive calls from the PSTN network through NetMeeting 3.0 or later.