The first thing you need to figure out is that the Microsoft Phone system is available in your country. This phone system requires you to have a Microsoft 365 license. The steps to get a Phone system are the same as acquiring a license for Microsoft 365. By using Direct Routing from your local Telecom Provider, you can have any available national or international Calling plan from them. The next step is to get Phone numbers for your users. Your existing phone numbers can also be ported while you choose the Microsoft Phone system.
Microsoft provides full-fledged documentation for setting up Microsoft Phone systems. You might want to get in touch with an expert.
Get in contact with a MachCloud expert to deal with setting up a Microsoft Phone system at your end.