WHAT IS VOIP
VoIP stands for voice over Internet Protocol (usually read as "Voice over IP"), a telecommunications system that uses the Internet or other Internet Protocol networks to transmit telephone calls. This technology is used for business phone systems and allows you to save money by having no line rental or pay high cost per minute call charges and is used by business phone system. You can connect with a ip phone or through your computer to call people.
WHAT IS A VOIP PBX SERVER (IP PBX)
An IP PBX or VOIP phone system replaces the traditional PBX or wired phone system and gives small and medium sized businesses the ability to setup a professional phone system with an easy to use web based interface. You can dial each other free of charge, setup voice mail, Music-on-hold, IVRs and much more. All phone calls are sent over the internet instead of the traditional phone network. You can connect existing phone lines to the IP PBX and make and receive phone calls via a regular PSTN line if required.
UK VOIP VPS FEATURES
Web-based management and administration
To make it quick and easy to manage your phone system directly from a web browser – this can include the ability to add end-user configuration and management functions as well
Automated attendant
An automatic system to answer phones with the ability to build phone menu systems, add call menus, transfer to voicemail and create flexible and programmable rules to handle all of these features.
Call menus
Flexible call management menus with user selectable options – a more advanced version of the traditional phone tree/menu systems. A better quality system will allow you to have multiple sets of menus and even change them based on time or on information gleaned from caller ID.
Managing extensions
Features to help the phone system administrator by allowing the addition of new extensions, removal of unneeded extensions, change of extension locations and much more from a web-based control panel
Voicemail and voice mailboxes
Any IP-PBX should allow an almost infinite number with far more flexibility than regular phone systems – more advanced features would include the ability to record ALL incoming and outgoing conversations automatically.
Call forwarding
Automatic, programmed or manual call forwarding to any number
Call hold
Placing callers properly on hold with no drop off in queues with user selectable hold music and programmable options about handling hold time length.
Conference calling
Handling multi-party conference calls – internally and externally
Branch office support
The ability to manage and remotely administer extensions at other offices just as easily as if they were local
99.99% Uptime SLA
Online Control Panel 
On Hold Music
