The good news is, getting your phone system from the cloud actually works! The bad news is, it takes some sorting out which subscription users need, to make it happen, adding the right packages, assigning phone numbers and conference bridges and how to manage numbers in your system, for the long haul. After all the promise of zero hardware to support is enough to seriously consider signing your office up for an Office 365 subscription to future proof your organizations opportunities in the cloud!
The idea of using your Office 365 subscription to upgrade your on premise phone system seems very promising! The issue is understanding what you need to make it happen. To start with, you must have an Enterprise E3 minimum, E5 comes with the Phone System on every subscription, E3 does not, you have to add it on after you purchase your E3 subscription.
This just gets you the Phone System, you still need to port or purchase phone numbers to use for your organization, and finally, purchase a calling plan that will allow you to call domestically or domestic and internationally, both plans come with 3000 pooled minutes. If you go beyond that you can purchase Communication Credits to fill the gap, or purchase an additional Domestic Calling Plan for another 3000 minutes.
To add on an Audio Conference license for your users to have a dial in number in every meeting invite they send for a Teams meeting, you will need to purchase the service as an Add On for each user, and then assign it to the users who need to have a dial in number for meetings. This Add On can be purchased for any Business Plan as well as for the Enterprise accounts. To be clear about this, if you purchase E3 or E5 you will need to purchase this Add On in addition to the Phone System for E3 and just as an Add On for E5.