he following numbers should not be assigned within a domain because they are reserved for system functions.
| Restricted Numbering | |
| 00-99 | Reserved for internal use |
|
611 |
Customer Service |
| 911 | Emergency |
|
700-799 |
Used for Dynamic Call Parking Queues |
|
5000/9900 |
Unregistered Login to VMail (prompted for acct no and password) |
|
5001/9901 |
Registered Login to VMail (prompted for password only) |
|
5002/9902 |
Hot Desking Sign In |
| 7000-7999 | These are unusable as extension numbers because they conflict with the 7+extension rule to transfer a call directly to voicemail |
| 9900-9999 | System Features |
| Best Practice Dial Plan | |
|
100-599 |
User Extensions |
| 800-899 | User Extensions |
| 1000-4999 | User Extensions |
| 5003-6999 | User Extensions |
| 8000-8999 | User Extensions |
| 9000-9899 | Special Extensions (Example : Cloud Extension that forward to a cell phone, Fax Users, call routing, call queues and auto attendants) |
