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Overview

Phone number extensions allow multiple phone lines to branch off from a single direct inward dialing (DID) number or main line. This setup is common in offices or call centers where individual desks or employees need unique extensions. The system has two components:
  • Route number: The primary phone number (also called the “main” number) that serves as the gateway for incoming calls before they are directed to specific extensions.
  • Extended numbers: Short digit sequences appended to the route number that connect callers directly to specific endpoints like departments or individuals.
For example, if the route number is +49 20 12345678, extensions might include +49 20 123456780 or +49 20 1234567806. When porting extended numbers, you first create a porting order with the route number, then attach the extensions to that order before submission.

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Constraints

  • Extended number porting is currently only available for German port orders.
  • Extensions can only be added while the porting order is in draft, in-process, or exception status.
  • The maximum extension range is 0 to 999.
  • Activation ranges must be equal to or a subset of the extension range.
  • Activation ranges cannot overlap.

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Extension range and activation ranges

Extensions are created in blocks defined by two parameters:
  • extension_range: Represents the full range of extensions available for the route number. This typically covers 10 numbers (0-9), 100 numbers (0-99), or 1000 numbers (0-999). All extensions within this range will port with the route number.
  • activation_ranges: Specifies which extensions within the extension_range should be active immediately upon port completion. Extensions not included in activation_ranges will port but remain inactive on your account.
For example, if your route number is +49 20 12345678 and you want to activate only extension +49 20 123456784:
  • Set extension_range to 0-9 (covering +49 20 123456780 through +49 20 123456789).
  • Set activation_ranges to 4-4 (activating only +49 20 123456784).
For multiple non-contiguous extensions like +49 20 1234567804, +49 20 1234567819, +49 20 1234567820, and +49 20 1234567842:
  • Set extension_range to 0-99.
  • Set activation_ranges to include 4-4, 19-20, and 42-42.

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How it works

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Step 1: Create a porting order with the route number

Create a porting order that includes the route number (the main DID). Do not include the extended numbers in the initial order.

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Step 2: Retrieve the porting phone number ID

Use the List all porting phone numbers endpoint to retrieve the porting_phone_number_id for your route number. You will need this ID to attach extensions.

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Step 3: Add extensions to the porting order

Use the Create a phone number extension endpoint to attach extensions to your porting order. Provide the porting_phone_number_id, extension_range, and activation_ranges in your request.

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Step 4: Submit the porting order

Once extensions are attached, submit your porting order through the standard porting workflow. The route number and all extensions within the extension_range will port together.

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Manage extensions

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View extensions

The route number appears in the List all porting phone numbers response, but extended numbers do not. To view extensions attached to a porting order, use the List all phone number extensions endpoint.

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Delete extensions

To remove extensions from a porting order before submission, use the Delete a phone number extension endpoint. The order must be in draft, in-process, or exception status.