Direct answer
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A UCaaS platform is built from business calling, meetings, and messaging with presence. Calling is the phone system, and meetings and messaging are the collaboration tools around it. Apps on a computer or mobile carry all three, and desk phones carry calls. What makes it one service is that the apps and phones answer to the same phone system, and an administrator manages the same people and numbers remotely in that service.
UCaaS takes the PBX, the equipment that runs an office's phones, and puts it in the provider's data centers. Atlantech Online's UCaaS page says it in one line: the phone system isn't in the office, it's on Atlantech's cloud.
The PBX decides what happens to a call. It rings a group of phones in order, forwards a call to a mobile, parks it for someone else to pick up, or plays a menu to the caller. Atlantech's Business Line card lists that kind of feature: call forwarding, transfer, hunt groups, park and pickup, and sequential ring. The voice itself travels as VoIP, which means it moves as data over an IP network.
Calling outside the company is a separate piece, and it's the one to check first. A call to a customer's mobile has to cross to the public telephone network, and that takes a connection to a carrier. Some providers fold it into the plan. Atlantech's Business Line card lists a voice trunk with unlimited local calling and unlimited domestic long distance.
Microsoft sells it apart. Its Teams calling overview says calls between Teams users are handled in Microsoft's cloud and are unlimited. Calls to and from outside telephone numbers need Teams Phone licensing and a connection to the public telephone network on top. So "includes calling" can mean two different things on two providers' pages.
Meetings are video calls with screen sharing. Atlantech's page lists video conferencing along with desktop and file sharing, which lets people show a presentation or spreadsheet during a call.
Messaging comes with presence, the status beside a colleague's name that shows whether they're free, on a call or in a meeting. Presence is what connects messaging to the phone system, because it changes what you do next. If the person is on a call, you send a message. If they're free, you ring them. Atlantech says its presence indicator updates from phone and calendar status, and that people send messages from the softphone app.
These two components overlap with office suites that include meetings and chat. If your team already holds its meetings and chats in a suite it will keep, you don't need a second copy from the phone provider. Settle that before you compare plans, because it changes which tier you need.
A softphone is a calling app that takes the place of a physical phone. It runs on a computer, and the mobile app does the same job on a phone. The apps are where calling, meetings and messaging sit side by side. A desk phone, where an office keeps them, covers the calling part.
What makes these a component of the platform is that they all answer to the same phone system. Atlantech's page describes this through the dial plan, the set of rules for how extensions and numbers are dialed and routed. Its softphone's calling features are tied to the business dial plan, and its mobile apps for Android and iOS take business calls anywhere. That's what lets an employee answer a business call on a personal mobile and still reach colleagues by extension.
Which devices matter depends on the work. A receptionist may want a desk phone with buttons. A salesperson on the road may only ever open the mobile app. We look at that split in the UCaaS features that matter most for remote teams.
Administration ties the other components to the company's people and numbers. Someone has to add a new hire, assign a number, change which phones ring after 5 p.m. and remove a person who leaves. On a hosted platform that work is done remotely, with no visit to a phone closet. Microsoft's overview describes the pattern for Teams: administrators manage calling by remote management of the cloud service, through the Teams admin center or PowerShell.
Reporting belongs here too. Atlantech's page lists historical and live call data, custom reports and dashboards, and call recording with rating for quality review. A manager uses those to see when calls peak and how they're being handled.
Integrations connect the phone system to other software, and the word covers several different jobs. One is dialing: a salesperson clicks a number in the CRM and the phone system places the call. Another is logging: a finished call is written to the customer's record without anyone typing it in. A product can do one and not the other, so the question for a buyer is which job the connection performs. Atlantech's page says its service connects with helpdesk software and sales CRMs, and it names Google and Microsoft. We go through the setup in how to integrate UCaaS with a CRM.
A platform can have every component, and a given plan can still include only some of them. Atlantech's pricing shows how that works. Its Business Line starts at $12 per user per month, and the card lists calling features with unlimited local and domestic long-distance calling. Its Premium Line starts at $18 per user per month, and that card lists voicemail, conferencing, collaboration and a softphone.
Read against the components above, the first card names calling. The second is where conferencing, collaboration and the softphone are named. Both are advertised starting rates, so the quote sets the term, taxes and setup, and it confirms which features come with each line.
Features built for a call center sit at the edge of the list. Atlantech's softphone works with ACD, which distributes incoming calls among a group of agents. Its own FAQ draws the boundary by use: UCaaS supports individuals and teams, and CCaaS supports a call center, where queuing, routing and reporting requirements are substantially different. A team whose needs stop at ringing a group and distributing calls can find that inside a UCaaS platform. A team that needs deeper queue management and agent reporting is describing the other category, which we compare in the difference between CCaaS, UCaaS and CPaaS.