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Reserved Number Space

The following numbers should not be assigned within a domain because they are reserved for system functions.

Restricted Numbering  
00-99 Reserved for internal use
411 Information
611 Customer Service
911 Emergency
933 Emergency Testing
988 National Suicide Hotline
700-799 Used for Dynamic Call Parking Queues
900-999 Reserved due to 911 system feature
5000/9900 Unregistered Login to VMail (prompted for acct no and password)
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
9999 Hot Desk/Hoteling Deactivate

Refer to the following table for assigning users or handling call routing.

Best Practice Dial Plan  
100-599 User Extensions
800-899 User Extensions
1000-4999 User Extensions
5003-6999 User Extensions
8000-8999 User Extensions
9000-9399 User Extensions
9400-9899 Special Extensions*

Although there is not a set method that must be adhered to for special extensions, we generally recommend the following groups for ease and convenience. This also aids in faster troubleshooting scenarios.

Recommendation for Special Extensions  
9401-9499 Call Routing Users
9501-9599 Auto Attendants
9601-9699 Call Queues
9701-9799 Conference Bridges
9801-9899 Miscellaneous
(Cell Phones, Fax Users, VM Box)

If you have any questions as it relates to the number space within ColTech Voice then please reach out to our support team.

Updated on November 24, 2022

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