Having found myself in a smaller country and subsequently the home of smaller businesses I have come up against a large show stopper in the past when talking Cloud PBX.

Previously, if you wanted to add Phone System licensing to your users they would need to be licensed as at least E3. This has made adding dial tone to users on Business Essentials or Business Premium a really large jump in licensing cost.
In a nutshell, Microsoft 365 Business Voice is an add-on license that can be added onto Office 365 or Microsoft 365 subscriptions that include Microsoft Teams.
Qualifying plans are:-
Office 365 Business Essentials, Business Premium, E1, E3, A3, or A3; Microsoft 365 Business, E3, or A3
NOTE No more than 300 users.

Currently Microsoft 365 Business Voice is available in Canada and the UK only, with more countries rolling out soon. New Zealand is rumored for sometime in 2020, keep an eye out for a formal announcement.
Microsoft 365 Business Voice is available worldwide from 1 April 2020!
You can either purchase your calling plans from Microsoft or make use of a telco of your own choice by means of Teams Direct Routing.
This is great news for the New Zealand market!
Reference https://www.microsoft.com/en-gb/microsoft-365/business-voice