Understanding SIP Trunking
Understanding SIP trunking takes a little bit of background information. This is a snapshot of what has come before it: an employee, such as a manager, dials an internal number with an analog phone system. The manager’s call then goes through an onsite or private branch exchange (PBA) in which the PBX is the central switching unit that controls both voice and data. At the end of the call, the manager has either the option of going to a voicemail box or returning to the conference call to discuss further issues.
With SIP, a computer server handles the routing of calls between the two different phones. The PBX provides the interface between the external system and the employees within the organization. When the call comes into the PBA, the administrator can route the call to one of the several other external call agents. When the call leaves the PBA, the administrator can route the call to an internal PBX. This is known as SIP Trunking.
Before SIP, a company used a centralized switching center that was located inside the company and handled all of its internal communications. Each employee had to go through the same set of internal employees who would handle their own calls. This was not only very inefficient, but it also created duplication within the communications department as employees would have to route their own calls through the internal system in order to keep up with internal communications and to get the calls to the proper place within the company.
By the early 1990s, the company began to move from centralized switching centers to distributed switches, which are now called SIP trunks. This is where the concept of SIP trunking originated. The distributed switch is a router that is placed at each location in the network, which allows multiple users to connect to a centralized switching unit. This allows the company to manage the call routing, and the connection between the internal and external systems while still maintaining the security of the company’s private information.
SIP trunks provide all the features of the centralized switches except for the central control station, which is what many of the customers think of when they think about these systems. The SIP trunks do, however, manage the internal call routing process. and allow companies to use multiple internal PBXs at once. Instead of having to have one centralized switch, the employees can make calls to multiple PAs and still have complete control over the call routing.
Because of the complexity involved in managing and controlling the routing of calls, SIP is very efficient. The company’s servers provide the necessary software and hardware that make routing of calls easy to maintain. The administrator can easily determine when a call should be routed by the PAs in the company or when the call should be forwarded to another PAs based on parameters set by the company. Since all of the internal PAs have the ability to communicate, the administrator can also troubleshoot routing problems that might arise if there are problems with the internal system or the external system. In addition, the administrator can also configure the system so that it works best for the company’s business model.
Although SIP is a very efficient way to keep all of the internal calls routed the right way, it is not as efficient as using a centralized switching unit. If one company is using SIP, the calls can easily go back and forth between offices, thus creating more overhead than with a centralized unit.
There are many different types of SIP trunks, such as MPLS, Wide Area Networks (WAN), and Bridged Networks. Each type of trunk is optimized for a specific function, so a company has to consider what function their trunks perform before choosing the right one for them. This will help the company decide how to optimize their network.