Voice over Internet Protocol or VoIP, is basically the process of sending voice through internet protocol, making it possible for a consumer to make phone calls at cheaper price. VoIP can be used as a complete replacement for phone lines at a location, or as supplementary trunking for additional capacity or lower cost for outbound long distance and inbound toll free.

"SIP Trunking" is just another name for VoIP. SIP stands for Session Initiation Protocol, and is the most common type of SIP. Some IP telephone system manufacturers use non-standard, proprietary data protocols, making it difficult to connect them to standard SIP networks.

When VoIP is properly engineered and the customer has Internet access of sufficient auality and capacity, it is very hard for customers to notice the difference between it and a normal telephone. Even the person who is receiving the calls from a VoIP will not be able to guess that the calls are made from a VoIP Network. Transferring PSTN (Public Switched Telephone Network) to VoIP/SIP Session Initiation Protocol) allows VoIP users to send and receive phone calls as done in ordinary phone lines.

VoIP is used for several reasons: To lower cost, to add features and to tie multiple locations together. 90% of VoIP vendors focus only on the first reason.  The customer should of course start from a basic cost saving perspective, but should then look at "the big picture" savings based on features and tying multiple locations together.

VoIP can be connected to an existing phone system in two ways: