Our phone system has the very odd name of Marco UCaaS. UCaaS stands for Unified Communication as a Service. "Unified Communication" means it's more than just a phone system. It is voice calls, chat and collaboration tools. It also includes "presence" meaning the ability to see if someone is available. "As a service" means we're hosted in the cloud and pay monthly for a service without owning the equipment.
Marco UCaas is built on Mitel tools. We have Mitel phones and services. For example we have "MiCollab" (kind of a mix of Mitel and My) which is a Mitel product. Marco provides all our support. They're the same company we use to lease our printers.
Here's a quick 2 minute video on Marco UCaaS.