Number Plans for your VoIP PBX in New Zealand
IP PBX systems, such as those based on Asterisk provide a great deal of flexability and configurability. Gone are the days where we need to program these systems to need a number dialled to access an outside line. In this post I will go over some of my recommendations for how to number and set our your internal extenstions and destinations, to simplfy both internal and external dialing for your users.
This post applies to New Zealand systems only, as the recommendations are based on the current New Zealand Number Administration Deed
Recommendation – Dial ‘7′ for internal
I have found that ‘7′ seems to be the least common start digit for local NZ Number (The exceptions being a couple of regions in the 03 and 06 calling ranges – see caveat below)
It is my suggestion that you use ‘7′ to lead all of your internal number on your system. The reason for this is with nothing else in this range external to your organisation, it is an easy way for you to destinguish internal and external calls at the dialplan level, speeding up dialing at the endpoint, and eliminating the need for a number to access an ‘outside line’.
Use ‘7′ for all of your internal destinations, not just extension numbering, but any other dialable numbers like ring groups, hunt groups, PBX Features like Voicemail, Directory etc., IVRs and anything else dialable. Plan your numbering in advance and keep it Consistant (Same number of digits).
As a guide, assume that you may need up to 2x the numbering space as you expect to have users. This includes remote users or users who share desks. Use headcount rather than desk count here. Plan ahead – Don’t create extension space for 50 users if you know (Or even imagine) the organisation could have 500, or even 5000 users some time in the future. You don’t want to have to re-number every extension in the organisation at some point in the future.
The below table should give you an idea of the lenth you should make your numbering ranges, based on how many users you expect at peak
|
Number of Users |
Number of Digits |
|
1-5 |
2 |
|
6-50 |
3 |
|
51-500 |
4 |
|
501-5,000 |
5 |
|
5,001-50,000 |
6 |
Caveat: If you are in one of the few local calling area where there are local numbers starting with 7 you will need to modify this strategy. My recommendation would be to either A) Require area code dialing on all calls, local included or B) Modify your dial plan to allow for the additional digits required to have local and extension numbers in the same rule. This would mean, depending on your setup, you may need a timeout to start dialing on the shorter extension numbers, or if your device allows it, press # or ‘Dial’ to proceed the call.
