Are there Reserved extensions?

I ran Ito a weird problem today (version I set up a new extension 500. No problem. Then I tried to set up an extension 600. Couldn’t do it. Tried 5 or 6 times. Then I set up extension 800. No problem.

Are there extensions that cannot be used? Is 600 one of them?

There are extensions that certain modules default to using. I was messing with the voice mail blaster and it picks 500 as the first extension it uses. You can overide using 500 as the first extension if you want.

Ring groups use 6xx by default.

Other numbers such as 911 are reserved for other purposes in a numbering plan.

That explains it. Thanks. Is there a list somewhere that shows all the reserved numbers?

Use the Print Extensions module, it will show all info you need.