24

Note In this example, West router voice port 1/0 has two separate POTS dial peers associated with it. Dial peer 201 matches
calls beginning with the digit 9 and handles PSTN calls originating from the West router. Dial peer 601 matches calls
beginning with the digit 7 and handles calls to the PSTN originating from the East router.

Checking the FXO Configuration

If you configured your FXO interface according to the example described in the “Configuring FXO Interfaces” section on
page 23, you can place outgoing calls over the PSTN. If you have trouble placing calls, use the show voice port command to
make sure that the VIC is installed correctly. Use the show dial-peer voice command to make sure that the data you configured
is correct, and test the PSTN by connecting a handset directly to the PSTN outlet and placing a call.
Note See the “Configuring Quality of Service” section on page 31 if you need to improve the quality of voice connections.
Configuring E&M Interfaces
If you have more than a few voice users at each location, the cost of voice ports and routers and the effort needed to configure
dial peers for all the combinations of origins and destinations increases rapidly. In this situation, it might be more efficient to
use a PBX at each location to switch local traffic and direct incoming calls and then use E&M VICs to connect the PBXs over
an IP network.
Figure 20 shows a company with two offices, West and East. Each office has a PBX to operate its internal telephone network,
and the IP network carries voice traffic between the offices. Each PBX connects to an E&M VIC port in the router.
Figure20 Linking PBXs over the IP Network (Local Dial Peers)
To configure E&M voice ports, use the following commands beginning in privileged EXEC mode.
Both PBXs in the example shown in Figure 20 use E&M interface Type 2, with four-wire operation and immediate-start
signaling. The values for your configuration depend on your PBX and are available from your telecommunications department
or the PBX manufacturer. For more information about E&M interface configuration commands, refer to the “VoIP Commands”
chapter of the Cisco 1751 Router Software Configuration Guide.

Command Task

Step1 dial-type {dtmf | pulse} Select the appropriate dial type for out-dialing.
Step2 signal {wink-start | immediate | delay-dial} Select the appropriate signal type for this interface.
Step3 cptone {australia | brazil | china | finland |
france | germany | japan | northamerica |
unitedkingdom}
Select the appropriate voice call progress tone for
this interface.
Step4 operation {2-wire | 4-wire} Select the appropriate cabling scheme for this voice
port.
Step5 type {1 | 2 | 3 | 5} Select the appropriate E&M interface type.
22342
West East
408 555-xxxx E&M VIC
0/0 919 555-xxxx
192.168.11.3
dial-peer voice 111 pots
destination-pattern 1408555….
port 0/0
PBX PBX
Source
Destination
IP cloud