tailieunhanh - cisco voice over ip cvoice authorized self study guide phần 7

và chuyển tiếp các CO địa phương 234 tổng đài, hệ thống VoIP. Hệ thống PBX hoặc VoIP sau đó mở rộng vòng 234. Toàn bộ quá trình này là minh bạch để người gọi. Một FXS DID thân cây có thể nhận được chỉ có cuộc gọi trong nước, do đó một sự kết hợp của FXS, DID, | 178 Authorized Self-Study Guide Cisco Voice over IP CVOICE VoIP call the call leg that is set up in the inbound direction uses any supported codec for voice compression that is based on the requested codec capability coming from the source router. When a default dial peer is matched the voice path in one direction might have different parameters from the voice path in the return direction. This might cause one side of the connection to report good quality voice while the other side reports poor quality voice. For example the outbound dial peer has VAD disabled but the inbound call leg is matched against the default dial peer which has VAD enabled. VAD would be on in one direction and off in the return direction. When the default dial peer is matched on an inbound POTS call leg there is no default IVR application with the port. As a result the user gets a dial tone and proceeds with dialed digits. Interestingly the default dial peer cannot be viewed using show commands. In Figure 3-30 only one-way dialing is configured. Example 3-11 and Example 3-12 illustrate the configuration for this topology. The caller at extension 7777 can call extension 8888 because a VoIP dial peer is configured on Router 1 to route the call across the network. However no VoIP dial peer is configured on Router 2 to point calls across the network toward Router 1. Therefore no dial peer exists on Router 2 that will match the calling number of extension 7777 on the inbound call leg. If no incoming dial peer matches the calling number the inbound call leg automatically matches to a default dial peer POTS or VoIP . Dial Peer 2 Figure 3-30 Default Dial Peer 0 Example 3-11 Router 1 Configuration Router1 config dial-peer voice 1 pots Router1 config-dial-peer destination-pattern 7777 Router1 config-dial-peer port 1 0 0 Router1 config-dial-peer exit Router1 config dial-peer voice 2 voip Router1 config-dial-peer destination-pattern 8888 Router1 config-dial-peer session target ipv4 Example .