Voice Over IP

Voice Port Call Types Type of Call Example Local call One staff member calls another staff member at the same office. The call is switched between two ports on the same voice-enabled router. On-net call One staff member calls another staff member at a remote office. ... [full story]

On-Net to Off-Net Calls When planning a resilient call-routing strategy, it might be necessary to reroute calls through a secondary path should the primary path fail. An on-net to off-net call, as illustrated in Figure 3-7, originates on an internal network ... [full story]

CallManager-to-CallManager Calls As part of an overall migration strategy, a business might replace PBXs with a Cisco Unified CallManager infrastructure. This infrastructure includes IP telephones that plug directly into the IP network. Cisco Unified CallManager performs the same call-routing functions formerly provided ... [full story]

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 ... [full story]

PLAR Calls PLAR calls automatically connect a telephone to a second telephone when the first telephone goes off hook, as depicted in Figure 3-4. When this connection occurs, the user does not get a dial tone because the voice-enabled port that ... [full story]

Off-Net Calls Figure 3-3 shows an example of an off-net call. To gain access to the public switched telephone network (PSTN), the user dials an access code, such as 9, from a telephone that is directly connected to a Cisco voice-enabled ... [full story]

On-Net Calls On-net calls occur between two telephones on the same data network, as shown in Figure 3-2. The calls can be routed through one or more Cisco voice-enabled routers, but the calls remain on the same data network. The edge ... [full story]

Local Calls Local calls, as illustrated in Figure 3-1, occur between two telephones connected to one Cisco voice-enabled router. This type of call is handled entirely by the router and does not travel over an external network. Both telephones are directly ... [full story]

Voice Applications Different types of applications require specific types of ports. In many instances, the type of port is dependent on the voice device connected to the network. Different types of voice applications include the following: Local calls On-net calls Off-net calls Private line, automatic ... [full story]

Configuring Voice Ports Connecting voice devices to a network infrastructure requires an in-depth understanding of signaling and electrical characteristics that are specific to each type of interface. Improperly matched electrical components can cause echo and make a connection unusable. As another ... [full story]

Voice Interface Configuration After reading this chapter, you should be able to perform the following tasks: Configure analog and digital voice interfaces as new devices are introduced into the voice path Configure analog and digital voice ports for optimal voice quality Voice gateways bridge ... [full story]

Router R1's ping 10.7.7.2 Output R1#ping 10.7.7.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.7.7.2, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 16/19/24 ms [full story]

Router R3's show ip route Output R3#show ip route Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - ... [full story]

Router R2's show ip route Output R2#show ip route Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, ... [full story]

Router R1's show ip route Output R1#show ip route Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - ... [full story]

Router R3's Configuration interface Serial0 bandwidth 2000 ip address 10.7.7.2 255.255.255.0 encapsulation ppp clock rate 2000000 ! router eigrp 100 network 10.0.0.0 The results of the show ip route command, issued on all routers, should be ... [full story]

Router R2's Configuration interface Serial0/0 bandwidth 128 ip address 10.1.1.1 255.255.255.0 encapsulation ppp clockrate 128000 ! interface Serial0/1 bandwidth 2000 ip address 10.7.7.1 255.255.255.0 encapsulation ppp ! router eigrp 100 network 10.0.0.0 Example 2-3 ... [full story]

Router R1's Configuration interface Serial0 bandwidth 128 ip address 10.1.1.2 255.255.255.0 encapsulation ppp ! router eigrp 100 network 10.0.0.0 Example 2-2 shows a possible configuration for router R2. [full story]

Initial Configuration In this task, you will configure the routers in the lab topology for Layer 3 connectivity. Complete these steps: 1. Adapting the topology shown in Figure 2-50 to your own router interface, assign an IP address to the serial interface on ... [full story]

Navigating Your Hands-On Lab In this lab, you will construct and become familiar with the VoIP lab topology to be used in subsequent labs. The lab topology contains a total of three Cisco routers. However, some of the labs can be ... [full story]

Modem Pass-Through Modem pass-through, as illustrated in Figure 2-48, is similar to fax pass-through, except that there is a computer modem at each end of the connection. The two modems communicate directly with each other over a transparent IP connection. Figure 2-48. ... [full story]

Fax Pass-Through Fax pass-through occurs when incoming T.30 fax data is not demodulated or compressed for its transit through the packet network, as shown in Figure 2-47. The two fax machines communicate directly with each other over a transparent IP connection. Figure ... [full story]

T.37 Fax Store and Forward The T.37 standard for fax store and forward, as depicted in Figure 2-46, is a way of delivering faxed documents as e-mail attachments. T.37 works by scanning a document, converting that document to tagged image file ... [full story]

T.38 Fax Relay The T.38 approach to fax relay is similar to the Cisco approach, but represents the industry standard. Because T.38 is an open standard from the ITU, it is compatible between different vendors. A Cisco voice-enabled router can be ... [full story]

Cisco Fax Relay Figure 2-43 depicts a VoIP network set up for fax relay. Initially, fax calls are digitized representations of the contents on paper. The digitized bit stream is then converted to analog for transmission over voice circuits. If Cisco ... [full story]

Enabling VoIP Fax and Modem Transmission This section describes the implementation of fax and modem traffic over a VoIP network. It explores both Cisco Systems and standard implementations of faxing, as well as various methods used to transport modem traffic over ... [full story]

Channel Associated Signaling - E1 [View full size image] The time slots are numbered 1 though 32, although the channels are numbered 0 through 31, as shown in Figure 2-35. Multiframe time slots are configured as follows: Time slot 1 carries only ... [full story]

Framing and Signaling In the E1 frame format, 32 time slots make up a frame. A multiframe consists of 16 E1 frames, as depicted in Figure 2-35. [full story]

E1 Channel Associated Signaling In E1 framing and signaling, 30 of the 32 available channels, or time slots, are used for voice and data. Framing information uses time slot 1, while time slot 17 (E0 16) is used for signaling by ... [full story]

Channel Associated Signaling T1 [View full size image] T1 CAS has the following characteristics: SF has a 12-frame structure and provides AB bits for signaling. ESF has a 24-frame structure and provides ABCD bits for signaling. DTMF, or tone, can be carried in band ... [full story]

Robbed-Bit Signaling [View full size image] The A and B bits can represent different signaling states or control features (on hook or off hook, idle, busy, ringing, and addressing). The robbed bit is the least significant bit from an 8-bit word. ESF ... [full story]

Signaling System Interoperability In some implementations, it is necessary to convert from one signaling format to another. Conversion is necessary to allow different systems to signal each other. Figure 2-42 illustrates an example of signal conversion. Figure 2-42. Signal Conversion Example The ... [full story]