• Article

Configuring Outbound Call Routing for Enterprise Voice

Topic Last Modified: 2009-05-22

Enterprise Voice routes specify how Office Communications Server 2007 R2 handles outgoing calls placed by Enterprise Voice users. These routes associate target phone numbers with particular media gateways and phone usage records. Office Communications Server 2007 R2 maintains a table of outbound call routes. When a user places a call, the server, if necessary, normalizes the phone number to E.164 format and attempts to match it to a SIP-URI. If the server is unable to make the match, it applies outgoing call routing logic based on the number. You define that logic in the form of a separate route for each set of target phone numbers that are listed in the location profile for each location.

When Office Communications Server determines that a dialed number needs to be routed to a PSTN gateway, the routing table is queried to determine the optimal gateway for the call. The dialed number and the policy of the calling user (or the user who transfers the call) determine the gateway to which the call should be routed. The ability to specify the PSTN gateways to which various numbers are routed enables you to determine which routes incur the lowest costs and implement them accordingly. Typically, you specify gateways by choosing the one closest to the location of the destination number in order to minimize long-distance charges. For example, if you are in New York and calling a number in Rome, you would carry the call over the IP network to the gateway in your Rome office, thereby incurring a charge only for a local call.

Configuring outbound call routing consists of instructing Office Communications Server how to route calls from Enterprise Voice users to phone numbers on the PSTN or a PBX. These routes populate the routing table, which embodies the outbound call routing logic that is followed by the server for PBX and PSTN numbers. An Enterprise Voice Route consists of:

  • A unique name and optional description that identify and describe the route.
  • One or more .NET regular expressions that specify target phone numbers that can use this route for outbound calls. The regular expression provides a numeric pattern to be matched to identify the target phone numbers to which the route is applied. The pattern-matching notation of regular expressions makes it possible to quickly parse large amounts of text to find specific character patterns; to extract, edit, replace, or delete text substrings; or to add the extracted strings to a collection in order to generate a report. Numbers that do not match the pattern of the target number cannot use this route. For details about specifying a route target regular expression using .NET regular expressions, and samples and descriptions of route target regular expressions (such as for creating a failover route, dialing emergency telephone numbers such as 911 or 999, setting up an international gateway, or blocking calls to specific numbers), see Routing Configuration Examples in the Planning and Architecture documentation.
  • One or more phone usage records that must be present in a caller’s Voice policy in order for that caller to place calls to target phone numbers associated with this route. The routing logic uses the phone usage record assigned to the caller and the dialed number in order to determine the optimal route. If a user's Voice policy does not include a phone usage record associated with this route, the user cannot to place calls to target phone numbers associated with the route. The order of phone usage records in Voice policies is significant, because the server compares phone usage records from top to bottom when it matches users to routes. If the first phone usage record matches the call route, the server quits looking and routes the call to the corresponding gateway. The remaining phone usages provide backup in the event of route congestion or call failure. To expedite call routing, the order of phone usage records should typically proceed from general to specific.
  • One or more media gateways or SIP trunks, and Mediation Servers that can handle routing for the target phone numbers.

To add a route, you must have previously deployed at least one media gateway or SIP trunk and, if necessary, Mediation Server, as well as a location profile and phone usage record. For a route to work, numbers routed to a gateway must be localized at the gateway, using the gateway’s administrative interface. For details about routes and how to plan for and implement specific routes, such as failover routes and other types of routes for specific purposes, see the Office Communications Server 2007 R2 Enterprise Voice Deployment Guide documentation and Planning for Voice in the Planning and Architecture documentation.

To create an outbound route

  1. On a Front End Server that has the Office Communications Server 2007 R2 administrative tools installed, open the Office Communications Server 2007 R2 snap-in.

  2. Right-click the Forest node, point to Properties, and then click Voice Properties.

  3. Click the Routes tab.

  4. On the Routes tab, click Add.

  5. In the Add Route dialog box, in the Name box, type a unique name for the new call route.

  6. In the Description box, type an optional description of the new call route.

  7. In Target phone numbers, use .NET framework regular expressions to describe the pattern of the phone numbers that are to use this route. To specify a target regular expression for target phone numbers, specify a combination of symbols and variables that represent the target numbers and their dialing patterns. For assistance, including a sample values, click Helper.

  8. To add a media gateway or Mediation Server to the Gateways list, click Add.

  9. In the Add Route Gateway dialog box, in the Select the Gateway Address drop-down list box, click the Mediation Server or Advanced Media Gateway to be added, and then click OK. The gateways and/or Mediation Servers that are correctly installed and configured appear in this list.

  10. To add a phone usage record to this call route, in the Add Route dialog box, under Phone Usages, click Configure.

  11. In the Configure Phone Usage Records dialog box, do the following:

    • To add a phone usage record to the Configured list, click the phone usage record in the Available list, and then click the right arrow. To add a phone usage record to a route, you must have previously defined at least one phone usage record.
    • To remove a phone usage record from the Configured list, click it, and then click the left arrow.

  12. When you are finished, click OK. The phone usages you added now appear in the list of Phone usage records in the Add Route or Edit Route dialog boxes.