To enable Operator Connect, go to Voice -> Operators and click on the All Operators tab. That will give you a list of all the Microsoft-approved telephone operators who are active in your area. Choose an operator (like CallTower, for example), then fill out the requested information, which will include the countries you want to be able to call and the number of people at your company who will need new phone numbers. Then, you'll receive a data transfer notice, and all you'll have to do is accept it. It's that easy.
Of course, some office workers have been entirely remote for almost two years now. Some have been remote for even longer. So it's not surprising that non-office-based work phones have existed, too. One option is the direct routing service, which is operated by the carrier. You provide a session border controller (SBC) that connects to your PSTN, which may be powered by Microsoft Teams or some other service, and the carrier connects it to the trunk. The advantage of direct routing is that you can choose any carrier and any PSTN.
One major plus of Operator Connect is its pricing model. You pay through Teams, and pay only for what you use. For that reason, you'll notice that it's significantly cheaper than old-fashioned phone services for an in-person office.
Another is that it's easier to use. That's partly because setup is a snap; a direct routing service probably has to be set up by your office's IT service, but most laypeople will be able to figure out Operator Connect. If your office is already using Teams for videoconferencing, you'll also have the advantage of having all your data in the same place. Contact lists, for example, won't need to be transferred to a completely separate service. Operator Connect is the choice for a company that needs limited phone service.
As businesses around the world go from in-person business to lockdown and back, temporary solutions are turning permanent, intentionally or otherwise. Now, it's as common to hear office workers complaining about glitchy VPNs and videoconferencing problems as it used to be common to hear them complaining about the office coffee machine. Like it or not, the way your office goes remote is part of its company culture, and will affect your employee retention rate and your ability to attract talent.
There are only two alternatives to the PTSN, neither of them good. One is to do all your networking through voice-only video conference. This tends to be fine for in-company communications, although video conferencing has a set of technological limitations. When making calls outside the company, though, you'll run into the problem that there are too many videoconferencing service providers. Often, either you'll have to use an unfamiliar service or your business partner will.
The other option is to use phones only. Tech companies have been issuing employees work phones for over a decade now, but this is an expensive proposition for a small company. On the other hand, expecting employees to use their own phones - and their own data - for work purposes saves the company money, but builds resentment. Most employees will resent having to use their own resources for company purposes.
Operator Connect offers a good middle ground for companies that want stable remote offices without running up the bills.