Hosted PBX --- A private branch exchange (PBX) is a telephone system that serves a particular business or office, as opposed to one that a telephone company operates for many businesses or for the general public. A hosted PBX system delivers PBX functionality as a service, available over the internet. Hosted PBXs are typically provided by the telephone company, using equipment located in the premises of the telephone company's exchange. This means the customer organization doesn't need to buy or install PBX equipment.
A hosted PBX allows a single number to be presented for the entire company, despite its being geographically distributed. A company could even choose to have no premises, with workers connected from home using a SIP Phone or SoftPhone and receiving the same features as any PBX user. One extension can ring (either concurrently or sequentially) in multiple locations. Employees can access the network using most high speed internet connections.
Virtual Servers --- A virtual private server (VPS, also referred to as Virtual Dedicated Server or VDS) is a method of partitioning a physical server computer into multiple servers such that each has the appearance and capabilities of running on its own dedicated machine. Each virtual server can run its own full-fledged operating system, and each server can be independently rebooted
Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft. It is part of the Microsoft Servers line of server products and is widely used by enterprises using Microsoft infrastructure solutions. Exchange's major features consist of electronic mail, calendaring, contacts and tasks; support for mobile and web-based access to information; and support for data storage
SharePoint Services --- Windows SharePoint Services allows web based document collaboration can be shared for collaborative editing. SharePoint provides access control and revision control for documents in a library.
SoftPhone --- a softphone is a software program for making telephone calls over the Internet using a general purpose computer, rather than using dedicated hardware. Often a softphone is designed to behave like a traditional telephone, sometimes appearing as an image of a phone, with a display panel and buttons with which the user can interact. A softphone is usually used with a USB Headset.