A SIP Trunk is a connection between your business and your Internet service provider since it can help you enable to extend VoIPphone system outside your company’s firewall without the need of an IP gateway. This simplify configuration is easier and less money to spend on design, maintenance and upgrade. And because ITSPs imply services at very low cost and will help you save money your investment on having SIP trunk can provide you a very quick return on your investments. And with all the benefits that SIP Trunk system can provide it’s no wonder that SIP Trunking is one of the hottest topic in telecommunications nowadays. From here onward we will discuss the popularity of SIP Trunk and it’s benefits , we will give an overview on how to deploy the system. A SIP Trunk can be deployed over the cloud system or over a phone line that is dedicated to your business and can share not may not share bandwidth with other Internet Protocol traffic. A line between your business and the ITSP usually will costs more expenses but it can also typically carry almost all of the calls and offers a very high security and reliability. And if your business can lower call volumes or lessen stringent security and available requirement. A SIP trunk can connect your business to a ITSP through the help of your existing IP-PBX or a Mediation server. Mediation server will perform encrypting and decrypting data translation between and Office Communications server. Each mediation server can have two interfaces and external and internal interfaces. The external interface is commonly called a gateway interface because this phone system usually connects to a IP-PSTN gateway or a IP-PBX system when you deploy SIP trunking however your external interface is connected to the SIP trunk. A SIP trunk can be deployed over the Internet or over a line that is dedicated to your organization and that may or may not share bandwidth with other IP traffic. A dedicated line (sometimes called a "leased line"-typically a T1 or fiber optic line) between your organization and the ITSP usually costs the most, In addition to VoIP calls, SIP trunks can also carry instant messages, multimedia conferences, user presence information but it can typically carry the most simultaneous calls and offers the highest security and reliability. If your organization has lower call volumes or less stringent security and availability requirements, another connection type might make sense for you.