Tail End Hop Off TEHO

TEHO extends the concept of toll-bypass. Instead of only routing intersite calls over an IP WAN link, TEHO also uses the IP WAN link for PSTN calls. The goal is to route a call using the IP WAN as close to the final PSTN destination as possible. As with toll-bypass, PSTN fallback should always be possible in case the IP WAN link fails.

Note Some countries do not allow TEHO. When implementing TEHO, ensure that the deployment complies with national legal requirements.

TEHO Example

Figure 7-25 shows the TEHO scenario for this example.

Figure 7-25 Tail-End Hop-Off Scenario Here is the process the call goes through:

1. Phone2-1 dials 9 1 408 555-6666 (that is, it places a call to a PSTN phone located in San Jose).

2. The call is routed to San Jose using the IP WAN link.

3. The local San Jose voice gateway is used to route the call as a local call to the San Jose PSTN.

4. The San Jose PSTN phone rings.

Configuring Site-Code Dialing and Toll-Bypass

To demonstrate the configuration of site-code dialing and toll-bypass, the following example walks through a configuration that meets these requirements:

■ All calls from Austin to San Jose should be routed using the WAN link if possible. If the WAN link fails, the PSTN link should be used.

■ Site codes must be used for intersite dialing.

Follow these steps to configure site-code dialing and toll-bypass:

Step 1. Configure voice translation rules and voice translation profiles for inbound and outbound VoIP intersite routing.

Step 2. Define the dial peers for VoIP intersite routing that route the call using the WAN link.

Step 3. Configure voice translation rules and voice translation profiles for inbound and outbound PSTN intersite routing.

Step 4. Define the dial peers for PSTN intersite routing that route the call using the PSTN link in case the WAN link is not available.

The following configuration scenario, as illustrated in Figure 7-26, will be used throughout this example:

■ Directory number range 2XXX

■ Directory number range 2XXX

Users should be able to reach other sites via site codes.

Users should be able to reach other sites via site codes.

Figure 7-26 Site-Code Dialing and Toll-Bypass Topology Example

Step 1: Create Translation Rules and Profiles

To create translation rules and profiles for intersite routing and path selection via the WAN, you can use the following procedure.

For each site:

Step 1. Create a rule that prefixes the site code to the calling number.

Step 2. Create a rule that strips off the site code from the called number.

Step 3. Create a voice translation profile to prefix the site code to the outbound calling-party number.

Step 4. Create a voice translation profile to strip off the site code from the inbound called-party number.

Examples 7-24 and 7-25 provide the resulting configurations on the San Jose router (that is, R1) and the Austin router (that is, R3).

Example 7-24 Step 1—R1

R1(config)#voice translation-rule 1

R1(cfg-translation-rule)#rule 1 /~2/ /S012/ R1(cfg-translation-rule)#exit R1(config)#voice translation-rule 2 R1(cfg-translation-rule)#rule 1 /'S012/ /2/ R1(cfg-translation-rule)#exit

R1(config)#voice translation-profile intersite-out

R1(cfg-translation-profile)#translate calling 1 R1(cfg-translation-profile)#exit R1(config)#voice translation-profile intersite-in R1(cfg-translation-profile)#translate called 2

Example 7-25 Step 1—R3

R3(config)#voice translation-rule 1

R3(cfg-translation-rule)#rule 1 /~2/ /S022/ R3(cfg-translation-rule)#exit R3(config)#voice translation-rule 2 R3(cfg-translation-rule)#rule 1 /'S022/ /2/ R3(cfg-translation-rule)#exit

R3(config)#voice translation-profile intersite-out

R3(cfg-translation-profile)#translate calling 1 R3(cfg-translation-profile)#exit R3(config)#voice translation-profile intersite-in R3(cfg-translation-profile)#translate called 2

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