Creating and Assigning Extensions

Creating and Assigning Extensions

Numbering Schemes

There are several schemes for assigning extensions. Invariably, though, you'll find the following guidelines will help:

• Use their previous extension numbers
  • Upgrading a system shouldn't require upgrading business cards
• Use the last 3 or 4 digits of their DIDs
  • Less for people to remember
• For non-DID systems, choose the last 3 digits of the main number
  • If the main number is 651-3200, then extensions can be 200, 201, 202, etc.
• Don't collide with system shortcuts, common dialing sequences, or emergency numbers
  • In the US, this rules out extensions in the 100s and 900s, at minimum. 611 and 311 shouldn't be assigned, but the rest of the 600s and 300s can be.
  • For FreePBX, 7777 is commonly 'simulate an incoming call', should be avoided, as should other Miscellaneous Destinations

Remember, when reserving DIDs, to get the whole block of interest if possible. It's usually low enough cost, and it really hurts to run out.