Global Private Branch Exchange (PBX) Market Assessment, By Type [On-premises PBX, Cloud-Based, Hybrid], By Solution [Devices, Software, Services], By Enterprise Size [Small Offices, Small Enterprises, Medium-sized Enterprises, Large Enterprises, Very Large Enterprises], By Industry [Finance, Manufacturing and Resources, Distribution Services, Services, Public Sector, Infrastructure], By Region, Opportunities and Forecast, 2018-2032F