Chapter 12. Voice and Telephony


This chapter presents several building blocks that can be used to implement a fully functional Voice over IP network. Transporting real-time, bandwidth-insensitive (or time-critical) voice traffic over a data network requires the use of many IOS features, possibly configured on many routers. You should carefully consider how to build such a network, adding a layer of complexity at a time. For example, you should approach a voice network in this fashion:

  1. Build a working IP network.

  2. Add the Quality of Service (QoS) features necessary for transporting voice at the appropriate places in your network. (Although it might be tempting to get voice traffic functioning first, getting QoS configured correctly at the start ensures that all of your voice traffic will be handled efficiently from the beginning. Scaling your network into the future then becomes easy.)

  3. Configure voice ports, where telephony devices will connect.

  4. Plan and configure an enterprise-wide dialing plan.

  5. Configure H.323 gateways in the appropriate locations.

  6. If the size of the dial plan and network topologies warrant , configure H.323 gatekeepers.

  7. Add additional voice functionality, such as Interactive Voice Response (IVR), Survivable Remote Site (SRS) Telephony, Media Gateway Control Protocol (MGCP), Session Initiation Protocol (SIP), debit card applications, settlement applications, and so forth.

NOTE

This chapter presents voice configuration for the Cisco 1700, 2600, 3600, 7200, 7500, and AS5x00 series routers and access servers. Voice configuration for the MC3810 and the 800 series routers is not covered.


This chapter discusses how to configure and use the following voice- related features:

  • 12-1: Quality of Service for Voice ” Recommendations for applying the necessary QoS tools at the necessary locations in the network.

  • 12-2: Voice Ports ” A router can connect to many different types of telephony devices using several types of voice ports. This section covers the many parameters that can be set or tuned on a voice port.

  • 12-3: Dialing ” Dial plans must be configured in order for calls to be routed correctly. A router handles calls by creating and maintaining connections between dial peers.

  • 12-4: H.323 Gateways ” The H.323 protocol is used to provide a way to send and receive voice, video, and data over an IP network. H.323 gateways provide communication between H.323 devices (VoIP nodes, Cisco CallManager, and so forth) and non-H.323 devices (POTS connections, PBXs, Cisco IP phones, and so forth). A router can be configured to function as an H.323 gateway.

  • 12-5: H.323 Gatekeepers ” An H.323 gatekeeper provides address translation between standard E.164 telephone numbers and IP addresses of H.323 nodes. A gatekeeper can also control and manage the registration and admission of new calls. Gatekeepers and gateways are arranged in a hierarchical fashion to scale a voice network.

  • 12-6: Interactive Voice Response (IVR) ” A router can perform IVR functions to interact with a caller when information is needed. Audio files can be played to the caller, prompting for various bits of information. Digits are then collected from the caller and can be used for authentication of the caller and authorization to make calls. Caller accounting can also be performed for statistics or billing information.

  • 12-7: Survivable Remote Site (SRS) Telephony ” When Cisco CallManagers are used to provide centralized call management for a network with Cisco IP phones, a remote site becomes dependent on its WAN link for phone service. SRS Telephony allows the remote site router to take over the CallManager's function if the WAN link or the CallManager fails. Users will still be able to make calls within the remote site and to the outside via the PSTN.



Cisco Field Manual[c] Router Configuration
Cisco Field Manual[c] Router Configuration
ISBN: 1587050242
EAN: N/A
Year: 2005
Pages: 185

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