IP (internet protocol) PBX systems give businesses greater flexibility by connecting phone numbers over the internet, potentially allowing employees to dial in remotely as well as providing additional features such as messaging and video conference calls. IP PBX phone systems use a process called SIP trunking (session initiation protocol). SIP is an application layer that enables you to run a phone service over your office network and connect phone systems over the Internet. For more information on these types of phone systems, visit our PBX and VoIP/SIP product webpage.