Direct answer
Every claim is sourced below
UCaaS (Unified Communications as a Service) is a cloud delivery model that bundles voice calling, video meetings, team messaging, and file sharing into one subscription platform [1][2]. A provider hosts the infrastructure and handles upgrades, replacing on-premises PBX hardware with per-user monthly pricing [3]. More than 45% of companies now run UCaaS as their primary communications platform [4].
Components
Provides enterprise telephony, DID numbers, call routing, voicemail, and PSTN connectivity over IP.
Hosts internal and external meetings with screen sharing, recording, and transcription from any device.
Delivers persistent chat, channels, direct messages, and real-time presence status across desktop and mobile apps.
Stores and shares documents inside the platform so files travel with the conversation rather than via email.
Lets users place and receive business calls on iOS, Android, desktop, and web with consistent identity.
Connects UCaaS into CRM, helpdesk, calendar, and SSO tools so call context flows into other workflows.
Key terms
Service type
Cloud-delivered unified communications platform combining voice, video, messaging, and collaboration tools under a subscription.
Technical dependency
Voice over Internet Protocol, the underlying technology that routes voice calls across IP networks instead of legacy phone lines.
Provider model
Provider-hosted phone system that replaces on-premises PBX hardware with internet-delivered call control.
Pricing model
Monthly or annual pricing model charged per active seat rather than as capex hardware investment.
AT&T Business