SIP users - If you are visiting this page than you know SIP means "Session Initiation Protocol."
SIP trunking is a digital phone service commonly used by businesses that operate their own VoIP PBX systems, which are sometimes referred to as IP-PBX phone systems. SIP is basically a scaled down service that provides basic call origination and termination service without all the other VoIP features like auto attendants, call conferencing, etc.
Instead, SIP users may use their own IP-PBX to provide these enhanced services. SIP is highly cost-effective because businesses only need to buy enough SIP trunks to match the maximum number of simultaneous inbound and outbound calls that they place. Even if a business has 50 extensions, they only need 15 SIP trunks if they calculate that they will only ever have 15 simultaneous inbound and outbound calls at one time (as opposed to 50 hosted VoIP trunks). Below, you will find the best SIP deals available.