Set Up Dialing Rules

A dialing rule establishes the permitted sequences of digits dialed on subscriber or station lines with subscriber premises equipment, such as telephones and private branch exchange (PBX) systems.

Set Up Dialing Rules

Create dialing rules for users

Dialing rule groups consist of dialing rule entries. Dialing rules are used to modify a phone number before sending it to an on-premises telephone system (PBX) or IP PBX for outgoing calls. Dialing rules serve two purposes:

  • They specify the numbers that can be dialed for outgoing calls. When you create a dialing rule, you specify the number formats that can be dialed. Any number that doesn’t match one of the formats you specified is rejected. If you don’t set any dialing rules, callers can place calls within your organization but can’t make any outgoing calls.
  • They transform the numbers dialed before sending them out to your on-premises telephone system. Dialing rules can strip numbers from or add numbers to the number dialed. For example, you can use dialing rules to add the outside line access code for your telephone system or to add or remove the in-country/region code for long-distance or local numbers.

To specify the types of outgoing calls you want to allow for a UM dial plan, you create a dialing rule group with dialing rules and then use them to authorize outgoing calls for Outlook Voice Access users and callers that dial into a UM auto attendant. You create separate dialing rule groups for in-country/region and for international calls.

Dialing plans in the public switch telephone network (PSTN) have traditionally been more commonly referred to as dialing procedures. The dialing plan of a private telephone system or a customer premise equipment, such as an analog telephone adapter(ATA), is sometimes also called dial plan. The digit sequences (numbers) permissible in a dialing plan may be as short as a single digit, e.g. for reaching an operator, or as long as a complete international telephone number, including trunk prefixes and international prefixes.

Examples of commonly used dialing rules

Number pattern Dialed number When would you use this dialing rule?
*** *** Allow all outgoing calls.
1425xxxxxxx 91425xxxxxxx Prevent users from getting an internal extension or an error when they forget to dial the outside access line number.
1xxxxxxxxxx 1xxxxxxxxxx Allow all numbers that start with 1.
xxxxxxx 1425xxxxxxx Add 1 and the local area code 425 to 7-digit numbers.

What do you need to know before you begin?

  • Estimated time to complete: Less than 3 minutes.
  • You need to be assigned permissions before you can perform this procedure or procedures. To see what permissions you need, see the “UM dial plans” entry in the Unified Messaging Permissions topic.
  • Before you perform these procedures, confirm that a UM dial plan has been created. For detailed steps, see Create a UM dial plan.
  • If you will be applying dialing rule groups to UM mailbox policies, you will need to confirm that a UM mailbox policy is created. For detailed steps, see Create a UM mailbox policy.
  • If you will be applying dialing rule groups to UM auto attendants, you will need to confirm that a UM auto attendant is created. For detailed steps, see Create a UM auto attendant.
  • For information about keyboard shortcuts that may apply to the procedures in this topic, see Keyboard shortcuts for the Exchange admin center.

Use the EAC to create a dialing rule

  1. In the EAC, navigate to Unified Messaging > UM dial plans. In the list view, select the UM dial plan you want to change, and then click Edit Edit icon.
  2. On the UM Dial Plan page, click Configure.
  3. On the UM Dial Plan page > Dialing rules, click Add Add Icon under In-country/region dialing rules or International dialing rules.
  4. On the New Dialing Rule page, enter the following information:
  • Dialing rule name: Enter the name of the dialing rule group you want this rule to be a part of. To combine it with other rules, use the same group name. To create a new dialing rule group, enter a new unique name.
  • Number pattern to transform (number mask): Enter the number pattern to transform before dialing, for example, 91425xxxxxxx. If a caller dials a number that matches, UM transforms it to the dialed number before placing the call. Enter only numbers and the wildcard (x). The number pattern is also called a number mask.
  • Dialed number: Enter the number to dial. Use only numbers and the wildcard (x), as in the number pattern 9xxxxxxx. Wildcards (x) are substituted with the digits from the original number dialed by the user. Make sure the number of wildcards in the dialed number is the same as the number of wildcards in the number pattern.
  • Comment: Enter a comment or description for this dialing rule. You can use the comment to describe what the rule does, for example, “Add a 9 to outgoing calls.”
  1. Click OK to save the dialing rule. You can continue to enter rules, using the same dialing rule group name for rules that you want to authorize together.


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