---
title: Forbidden Extension Numbers
description: Certain numbers can not be used as extension numbers.
---

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# Forbidden Extension Numbers

## Certain extension numbers are restricted due to potential conflicts with 911 services and the increased risk of misdials.

The following extensions are not permitted:

**000, 211, 311, 411, 611, 711, 811, 911, 933, 999**

When creating or deploying a customer, an error message will appear if an attempt is made to assign any of these restricted extensions.

See [FCC](https://www.fcc.gov/consumers/guides/dial-211-essential-community-services) for more information.

 

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