3CX is a software-based PBX solution with a cloud hosted option, offering users web conferencing, CRM integration, instant messaging, and native mobile apps.
Microsoft Office is a suite of desktop productivity applications and client and server software designed for data analysis, presentations and numeric manipulations.
Microsoft Office 365 provides web, desktop, and mobile apps for Outlook, Word, Excel, PowerPoint, OneNote, Publisher, Skype, OneDrive, Exchange Online, and more.