Voice & Video Calling platforms (Unified Communications as a Service, UCaaS) replace legacy PBX and on-premises voice infrastructure with cloud-delivered voice, video, messaging, and conferencing. Core capabilities include business voice with DID numbers and PSTN connectivity, video meetings across desktop and mobile, persistent team messaging, meeting recording and transcription, contact center adjacencies for customer-facing teams, call analytics and quality monitoring, and integration with the productivity suite and identity provider. UCaaS is the cloud-delivered successor to on-premises PBX and conferencing hardware.