7 digit dialing is a future feature looking to solve some limitations of the current dial plan.

Current issues:

• The entire dial space is 4 digits long - that means that there can only be 9,999 unique directory numbers.
• The first digit is treated as a site code, limiting the number of sites to 9. Sub-sites (i.e. borrowing space from the second digit) adds some space, but isn’t ideal.

Key terms:

• Dial plan (or dial space): the set of rules CUCM uses to route calls
• Site: a unique location - one CUCM server may support multiple sites (i.e. if a user doesn’t have their own CUCM server)
• NPA - numbering plan area - an area code like 415, 650, 214, or 845.
• NXX - central office/exchange code - the middle three digits of a phone number - for example the NXX for 212-444-5678 is 444.

Proposed solution:

• Each site will be assigned a 3 digit site identifier that will be treated as the NXX of the site.
• Users will be free to assign directory numbers within the entire 4 digit remaining space, meaning each site gets 9,999 possible directory numbers.
• In the case that users/sites have their own CUCM server, routes will be set for the NXX going to the trunk for the remote CUCM server.
• User sites can be assigned multiple NXX-style site identifier for different use cases such as radio repeater, IVR, etc.