# 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:

- Easy to configure; provides a single consolidated provisioning interface - the Direct Inward Dialing Services form.

- Speed Call System's limits do not apply:

- with DID Service, unlimited number of destinations can be configured;

- destination number can be up to 26 digits long (as opposed to 7 digits for System Speed Calls).

- DID and destination numbers do not have to be statically mapped one-to-one; multiple DID numbers can be assigned the same destination.

NOTES

- If enabled, the DID Service is applied to incoming DID calls after Trunk Attributes digit modification and System Speed Calls processing are completed.

- If your current DID implementation is based on the user-based System Speed Calls, it is strongly recommended that you migrate all currently configured DID numbers from the System Speed Calls form to the Direct Inward Dialing Services form before enabling the DID Service. See Migrating to DID Service for details.

### 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

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

- If the search returns conflicting multiple matches, no matches are used and the call is routed on the originally dialed digits.

- If a partial match is found, the call is routed on the originally dialed digits.

- In a rare conflict scenario where: FOPBX (Force-to-PBX) is configured as the CRS option in the Trunk Attributes form, both CRS and DID service are enabled, and the EHDU external number matches the DID number, the call will be handled by CRS and not DID Service.

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

- CRS query returns NO MATCH (no destination number is assigned to the DID number) because a suite or a Hotel Room Extension Not In Suite (HRENIS) to which the DID was assigned is now checked out. (This occurs only if the hotel option Cancel All Features on Check-Out is enabled.)

- DID destination number cannot be routed for any other reason.

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

- DID destination is out of service.

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

NOTES

- In any of the above scenarios,

- if a logged-in EHDU calls a DID number and the call has to be routed to intercept handler, the EHDU's intercept configuration is used;

- if an EHDU is not involved and the call has to be routed to intercept handler, the inbound trunk's intercept handler is used.

- Intercept handler for users is programmed through the Station Attributes form; intercept handler for trunks is programmed through the Trunk Attributes form.

## Conditions and Feature Interactions

- DID numbers can be mapped to any routable digits; however, the following destination number types require caution or are not recommended:

- Automatic Route Selection (ARS) Digit Strings - use with caution; possibility of toll fraud

- System Access Points - not recommended

- Feature Access Codes - not recommended

- Primary Node Identifier (PNI) - use with caution

- Cluster Element Identifier (CEID) - use with caution

- EHDU number - use with caution

- Original DNIS - use with caution

- In a rare conflict scenario where: FOPBX (Force-to-PBX) is configured as the CRS option, both CRS and DID service are enabled, and the EHDU external number matches the DID number, the call will be handled by the CRS and not the DID Service.

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.

- DID Service applies to incoming calls only. Outgoing DID calls are handled by CPN Substitution.

- In a Key Inquiry session, to view the configured DID Service number (public number or calling party number):

- On an idle phone, press the Superkey followed by the Prime Line key.

- During a call, press the Prime Line key.

- DID Service takes priority over System Speed Calls. When both are programmed to reroute the same calls DID Service routing is used.

## Programming

1. Trunk Attributes form

- Enable the "Direct Inward Dialing Service" option for the trunks.

2. Do one of the following:

- Fill out the Direct Inward Dialing Service form

2. 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.

NOTES

- You can configure the Direct Inward Dialing Services form first and then enable the DID service in the Trunk Attributes form, or vice versa.

- If desired, the DID number or DID ranges can be assigned to the existing destination numbers (System Speed Call numbers should be deleted).

- It is recommended that before using the DID Service feature, all nodes in the network (at least Trunking Gateways) be upgraded to Mitel MiVoice Business Release 7.0.

## 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

- Enable the "Direct Inward Dialing Service" option for the trunks.

2. Direct Inward Dialing Services form

- Provision all DID numbers and other fields for incoming DID calls.

3. System Speed Calls form i

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

- Export the System Speed Calls form into a csv file.

- Copy and paste required numbers into the Direct Inward Dialing Services csv import form.

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.

- Import the Direct Inward Dialing Services form.

- Delete the migrated numbers from the System Speed Calls form.

NOTES

- The respective DID numbers need to be assigned to the existing destination numbers.

- For outgoing DID calls, the existing CPN substitution will continue to function.

- The existing CRS types interwork with the DID Service.

## Device Support

Not applicable

## Operation

None

Related Topics

- DID Ranges for CPN Substitution

- Direct Inward Dialing (DID)

- System Speed Calls