Table of Contents

VoIP Configuration Examples

This section uses four different scenarios to demonstrate how to configure Voice over IP (VoIP). The actual VoIP configuration procedure depends on the topology of your voice network. The following configuration examples should give you a starting point, but you will need to customize them to reflect your network topology.

Configuration procedures are supplied for the following scenarios:

FXS-to-FXS Connection Using RSVP

The following example shows how to configure VoIP for a simple FXS-to-FXS connection.

In this scenario, a very small company with two offices decides to integrate VoIP into its existing IP network. One basic telephony device is connected to Catalyst 4224 RLB-1; therefore, Catalyst 4224 RLB-1 is configured for one POTS dial peer and one VoIP dial peer. Catalyst 4224 RLB-w and Catalyst 4224 RLB-e establish the WAN connection between the two offices. Because one POTS telephony device is connected to Catalyst 4224 RLB-2, it is also configured for one POTS dial peer and one VoIP dial peer.

In this scenario, only the calling end (Catalyst 4224 RLB-1) is requesting RSVP.

Figure C-1 illustrates the topology of this FXS-to-FXS connection example.

Configuration for Catalyst 4224 RLB-1

Configuration for Catalyst 4224 RLB-w

Configuration for Catalyst 4224 RLB-e

Configuration for Catalyst 4224 RLB-2

Linking PBX Users with E&M Trunk Lines

The following example shows how to configure VoIP to link PBX users with E&M trunk lines.

In this scenario, a company decides to connect two offices: one in San Jose, California, and the other in Salt Lake City, Utah. Each office has an internal telephone network using a PBX connected to the voice network by an E&M interface. Both the Salt Lake City and the San Jose offices are using E&M Port Type II, with four-wire operation and Immediate Start signaling. Each E&M interface connects to the Catalyst 4224 using two voice interface connections. Users in San Jose dial 801-555 and then the extension number to reach a destination in Salt Lake City. Users in Salt Lake City dial 408-555 and then the extension number to reach a destination in San Jose.

Figure C-2 illustrates the topology of this scenario.

Note   This example assumes that the company has already established a working IP connection between its two remote offices.

Router San Jose Configuration

Router Salt Lake City Configuration

Note   PBXs should be configured to pass all dual tone multifrequency (DTMF) signals to the router. Cisco recommends that you do not configure, store, or forward tone.

Note   If you change the gain or the telephony port, make sure that the telephony port still accepts DTMF signals.

FXO Gateway to PSTN

Foreign Exchange Office (FXO) interfaces provide a gateway from the VoIP network to the analog public switched telephone network (PSTN) or to a PBX that does not support Ear and Mouth (E&M) signaling.

In this scenario, users connected to Catalyst 4224 SJ in San Jose, California, can reach PSTN users in Salt Lake City, Utah, via Catalyst 4224 SLC. Router SLC in Salt Lake City is connected directly to the PSTN through an FXO interface.

Figure C-3 illustrates the topology of this scenario.

Note   This example assumes that the company has already established a working IP connection between its two remote offices.

Router San Jose Configuration

Router Salt Lake City Configuration

FXO Gateway to PSTN (PLAR Mode)

The following scenario shows an FXO gateway to PSTN connection in PLAR mode.

In this scenario, PSTN users in Salt Lake City, Utah, can dial a local number and establish a private line connection in a remote location. As in the previous scenario, Catalyst 4224 SLC in Salt Lake City is connected directly to the PSTN through an FXO interface.

Figure C-4 illustrates the topology of this scenario.

Note   This example assumes that the company has already established a working IP connection between its two remote offices.

Router San Jose Configuration

Router Salt Lake City Configuration