In tại Hoa Kỳ của Mỹ Thư viện In ấn đầu tiên năm 2008 tháng bảy của Quốc hội mục-trong-Xuất bản dữ liệu Bắt đầu hoạt động bằng cách sử dụng mặt đất và thiết bị dò hiện tại cho phép mạng lưới để chỉ móc hoặc giữ cuộc gọi đến độc lập của các tín hiệu chuông và | 128 Authorized Self-Study Guide Cisco Voice over IP CVOICE Figure 3-4 PLAR Calls An example of a PLAR call is a client picking up a customer service telephone located in the lobby of the office and being automatically connected to a customer service representative without dialing any digits. The call is automatically dialed based on the PLAR configuration of the voice port. In this case as soon as the handset goes off hook the voice-enabled router generates the preconfigured digits to place the call. PBX-to-PBX Calls PBX-to-PBX calls as shown in Figure 3-5 originate at a PBX at one site and terminate at a PBX at another site while using the network as the transport between the two locations. Many business environments connect sites with private tie trunks. When migrating to a converged voice and data network this same tie-trunk connection can be emulated across an IP network. Modern PBX connections to a network are typically digital T1 or E1 with channel associated signaling CAS or Primary Rate Interface PRI signaling although PBX connections can also be analog. Note PBX-to-PBX calls are another form of toll-bypass. An example of a PBX-to-PBX call is one staff member calling another staff member at a remote office. The call is sent from the local PBX through a voice-enabled router across the IP network through the remote voice-enabled router and terminated on the remote office PBX. Chapter 3 Routing Calls over Analog Voice Ports 129 Intercluster Trunk Calls As part of an overall migration strategy a business might replace PBXs with Cisco Unified Communications Managers. This includes IP phones connected to the IP network. Cisco Unified Communications Manager performs the call-routing functions formerly provided by the PBX. When an IP phone call is placed using a configured Cisco Unified Communications Manager the call is assessed to see if the call is destined for another IP phone under its control or if the call must be routed to a remote Cisco Unified .
