Configuring Voice over IP for the Cisco 3600 Series

Voice over IP (VoIP) enables a Cisco 3600 series router to carry voice traffic (for example, telephone calls and faxes) over an IP network.

Voice over IP is primarily a software feature; however, to use this feature on a Cisco 3600 series router, you must install a Voice Network Module (VNM).

The VNM can hold either 2 or 4 Voice Interface Cards (VICs). Each VIC is specific to a particular signaling type associated with a voice port; therefore, VICs determine the type of signaling for the voice ports on that particular VNM.

Voice over IP offers the following benefits

Toll bypass , Remote PBX presence over WANs , Unified voice/data trunking , POTS-Internet telephony gateways

Prerequisites Tasks

Establish a working IP network . Install the one-slot or two-slot (NM-1V/NM-2V)

Establish a working telephony network based on your company's dial plan

Integrate your dial plan and telephony network into your existing IP network topology. Merging your IP and telephony networks depends on your particular IP and telephony network topology.

Use canonical numbers wherever possible. It is important to avoid situations where numbering systems are significantly different on different routers or access servers in your network.

Make routing and/or dialing transparent to the user—for example, avoid secondary dial tones from secondary switches, where possible.

List of Terms

Call leg—A logical connection between the router and either a telephony endpoint over a bearer channel or another endpoint using a session protocol.

ACOM - ACOM is the combined loss achieved by the echo canceller, which is the sum of the Echo Return Loss, Echo Return Loss Enhancement, and nonlinear processing loss for the call.

Channel Associated Signaling (CAS)—A form of signaling used on a T1 line. With CAS, a signaling element is dedicated to each channel in the T1 frame

CIR—Committed Information Rate. The average rate of information transfer a subscriber

CODEC—Coder-decoder compression scheme or technique. In Voice over IP, it specifies the voice coder rate of speech for a dial peer.

Dial peer—An addressable call endpoint. In Voice over IP, there are two kinds of dial peers: POTS and VoIP

VoIP dial peer—Dial peer connected via a packet network; in the case of Voice over IP, this is an IP network. VoIP peers point to specific VoIP devices.

 DTMF—Dual tone multifrequency. Use of two simultaneous voice-band tones for dial (such as touch tone).

 E&M—Stands for recEive and transMit (or Ear and Mouth).

FIFO—First-in, first-out.

FXO—Foreign Exchange Office

FXS—Foreign Exchange Station

Multilink PPP—Multilink Point-to-Point Protocol.

PBX—Private Branch Exchange

PLAR—Private Line Auto Ringdown

PVC—Permanent Virtual Circuit

RSVP—Resource Reservation Protocol. This protocol supports the reservation of resources across an IP network