It always is difficult to say with certainty how big a market unified communications represents. It is a mix of enterprise hardware and software (room videoconferencing systems, phone systems, for example) plus software and managed services (unified communications as a service), access services (SIP, for example), consulting and maintenance contracts. By some estimates, the global market in 2020 is about $12 billion.
Others believe the the unified communications as a service (UCaaS) market alone represented about $16 billion in annual revenues in 2019.
Gartner estimated North America UCaaS spending having growth rates of 20 percent in 2019, for example, representing sales of about $2.1 billion.
Such figures explain why unified communications, either premises-based or delivered as a managed service, has been the province of specialists (integrators, interconnect companies, VoIP specialists, PBX suppliers). The market is too small to be of major interest to a tier-one service provider.
At least in the U.S. market, any opportunity representing less than $1 billion in sales for any single firm is too small to chase.