SIP Trunking - Overview
What is a SIP Trunk?
First let us define what a "trunk" is. The trunks are the telephone lines coming into a phone system from the telephone provider. Some phone systems have multiple analog lines (also know as land-lines), others may have one or more PRI's or a T1's. Basically a SIP Trunk is a VOIP trunk coming into your phone system.
So why should you think about switching to a SIP Trunk?
The quick answer is to save money on your telecommunication costs. However SIP lines allow for many more features than a analog line can provide. The feature set is very similar to a PRI or a T1. For instance if you would like direct inbound dial (DID) numbers, an analog line cannot handle this. A DID number is usually used to give each phone its own private number so a customer can dial them directly. SIP Trunks can provide this feature.
How can you tell if my PBX can handle a SIP trunk?
The best place to check is with the vendor of your PBX. Some phone systems may need an update to handle this, others may not have the capability of ever handling a SIP trunk. However, you can get a device called a session border controller. This is a device that provides security to the SIP trunks but some can also convert them to analog lines. So if your system already supports analog trunks, then a session border controller may allow you to use SIP trunks. Please be aware that some features like DID may not be supported when using a session border controller.
What is the difference between a metered plan and an unlimited plan?
A metered plan is a plan that you pay for what you use. A metered plan can be more or less expensive depending on your usage. An unlimited plan allows you to use as many minutes as you need.