Direct Inward Dialing (DID) Service

Description

This feature provides the ability to reallocate DID numbers to their answering points, so the incoming DID calls are routed directly to specified destinations. The Direct Inward Dialing Services form is used to map DID numbers to their destinations, but the configured data is saved, stored in, and retrieved from the Call Recognition Service (CRS) database. Use the Call Recognition Service form to search and view DID records.

Both the Direct Inward Dialing Services and the Call Recognition Service forms are not mutually exclusive and can be enabled at the same time. See Conditions and Feature Interactions for information on a rare conflict scenario.

The DID Service solution is an alternative to digit modification through the Trunk Attributes form and user-based System Speed Calls (i.e., the "old" way of provisioning DID), with the following benefits:

NOTES

 

Incoming DID call processing algorithm

  1. Trunk service digit modification is performed, based on the incoming trunk configuration.

  2. System Speed Calls lookup is conducted.

  3. CRS database is searched for the modified DID number and the associated destination number.

Possible CRS query responses:

NO MATCH - no associated destination number found

EXACT MATCH - the exact one associated destination number found

CONFLICTING MULTIPLE MATCHES - more than one associated destination number found

PARTIAL MATCH - one or more matches associated with the subset of queried digit string found

  1. If an exact match is found in the CRS database, the call is routed to the destination number. Otherwise, the following routing is applied:

In the following circumstances a call cannot be routed to its destination and an appropriate intercept handling is applied:

In the above scenarios, Intercept Handling for "Unassigned Directory Number" is applied and the Reorder Tone is returned.

In this case, Intercept Handling for "Directory Number Out of Service" is applied and the Reorder Tone is returned.

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Conditions and Feature Interactions

If an EHDU makes a DID call (DID number hosted by the EHDU's home node), both CRS and DID services will be applied to the call and the query will find both the EHDU and the DID destination. This query will be performed at trunking gateway only.

Programming

  1. Trunk Attributes form

  1. Do one of the following:

  1. Enter a number in the DID Service Number field and select the Use DID Number for Outgoing Calls check box in the User and Services Configuration form.

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Migrating to DID Service

Depending on your current use of the System Speed Call Numbers for the user-based DID routing, it may not be possible to take advantage of the new DID Service until all DID numbers currently configured in the System Speed Calls form are migrated to the Direct Inward Dialing Services form. Having DID numbers configured in both System Speed Calls and Direct Inward Dialing Services forms can result in incorrect DID routing and/or the new DID Service not being used.

For example, the System Speed Call Numbers are limited to seven digits, so any CO-supplied DID numbers longer than that require digit modification on the inbound trunk via the Trunk Attributes form. This means the System Speed Call-based DID numbers are not the full DID numbers of the users but rather their abbreviated versions. However, any new user number added to the Direct Inward Dialing Services form would be the full DID number provided by the CO. As a result, the Direct Inward Dialing Services lookup would not find a match for the abbreviated number and the call would not be routed properly or would be routed back to the System Speed Calls form.

Furthermore, it is likely that the same inbound trunks would be used for both your existing speed call-based DID numbers and the new DID Service numbers. Inbound DID calls to the new users would have the existing modification (via the Trunk Attributes form) applied to them and would not route correctly. 

DID numbers (the abbreviated versions) could be added to the Direct Inward Dialing Services form in the same manner as in the System Speed Calls form but that would defeat the purpose of the new functionality and would also obsolete the new DID/CPN Substitution support in the User and Service Configuration form.

For the reasons above, to take full advantage of the DID Service and to ensure correct incoming DID calls processing, it is strongly recommended that you migrate all existing DID numbers from the System Speed Calls form to the Direct Inward Dialing Services form.

To migrate from the System Speed Call-based DID configuration to the DID Service:

  1. Trunk Attributes form

  1. Direct Inward Dialing Services form

  1. System Speed Calls form i

To migrate currently configured DID numbers to the Direct Inward Dialing Services form, you can

NOTE: If you are currently using the Trunk Attribute form to modify the incoming DID digits, the newly migrated DID numbers should be appropriately modified to ensure that they constitute the full DID number, as provided by the CO. You may also need to modify the appropriate digit modification fields in the Trunk Attributes form.

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Device Support

Not applicable

Operation

None