SIP Trunking has nothing to do with luggage or elephants. It’s all about delivering modern telecom services. Trunking is a technical term that means using a single line or other communications path to transport many different transmissions simultaneously. The telephone industry had a pressing need for trunks to handle the explosive growth of telegraph and, later, telephone lines. Both wired and wireless analog carrier systems were developed to consolidate many telephone lines into a few trunks. This was especially critical for connecting telephone switching systems in different towns or states.
The trunk lines that we are most familiar with today are T1 telephone lines or ISDN PRI. These are two slightly different standards for a digital telephone line that carries as many as two dozen simultaneous phone calls. T1 or ISDN PRI trunks are very popular for corporate PBX phone systems or call centers. Both need large numbers of outside phone lines to communicate.
In actuality, ISDN PRI or Primary Rate Interface uses a T1 line to deliver 23 phone lines in individual digital channels plus one specialized channel used for switching, signaling and data such as Caller ID. The T1 voice or T1 telephone lines uses all 24 available channels for phone calls, but doesn’t offer Caller ID and has slower call setup times.
T1 lines are pretty versatile. A lot of companies have two T1 lines coming into the building. One carries IDSN PRI with anywhere between 10 and 23 outside phone lines. The other T1 line provides dedicated broadband Internet access for the computer network. The bandwidth is 1.5 Mbps for both upload and download. Even though there are two T1 lines installed, one has nothing to do with the other. They are electrically separate and may have been ordered from two different service providers.
The cost of two separate T1 lines is more than many smaller businesses can justify. They don’t need anywhere close to 23 outside lines, often less than half that, and 1.5 Mbps Internet access is plenty for credit card verification, online ordering, file transfers, email, and casual Web access. They could probably get by with half an ISDN PRI and half a T1 Internet line if they could buy half a service for each.
SIP Trunking gives you that half-a-service option by combining voice and data onto a single converged trunk line. That could be a T1 line or an Ethernet over Copper connection that uses the same twisted pair telco wiring but offers high bandwidth options. Actually, a single SIP trunk is better than two half-T1 lines. It also costs less than those two T1s you may have now.
The SIP in SIP Trunking stands for Session Initiation Protocol. That’s the switching technology used in VoIP telephone systems. A SIP phone is a VoIP telephone that can plug right into your network. Older analog phones can be turned into SIP phones by using Analog Telephone Adaptors (ATA).
Now, here’s what SIP Trunking does to consolidate lines. A SIP Trunk carries both voice and data simultaneously. It can do that because both are in the same packet network protocol. The broadband Internet data is already packetized. By using adaptors or SIP phones, the telephones are made to look like other network devices. Once everything is communicating in packets, a single line can transport both.
One question you probably have immediately is about how the SIP trunk prevents telephone conversations from being garbled when computers are sending data. Companies that have tried to use broadband phone services to share their Internet service find that performance is iffy. Sometimes the conversations sound good. Other times, not so good. That’s because the Internet doesn’t treat sensitive voice conversations any differently than file transfers or video downloads. One packet is just like the next on the internet.
A SIP trunk uses Internet technology, but it doesn’t use the Internet itself. The SIP trunk is a private line between your company and your service provider. Once your packets get to the service provider they are switched onto the Internet or onto the public phone system, depending on where they are supposed to go. The SIP trunk is engineered to ensure that telephone calls do not contend with data packets for use of the trunk line.
Here’s how that works. The interface equipment, managed routers, at each end of the SIP trunk are set up to establish Class of Service (CoS) for each of the many simultaneous signals that travel over the trunk. Telephone calls have priority in this system. Whenever a call is in progress, it takes the bandwidth needed to ensure high voice quality. Only the bandwidth not used for telephone calls is available to transport broadband Internet service. When a call hangs up, data packets can now use the additional bandwidth no longer commandeered by the phone call.
Obviously, you can’t have dozens of phone calls on a T1 line being used as a SIP trunk or your Internet access will slow to a crawl. Most small companies don’t have that problem. They may need only 6 to 12 outside lines at the most. Even those lines aren’t engaged 100%. The result is that there is plenty of bandwidth for both telephone calls and broadband access at the same time.
Efficiency is what makes SIP trunks a better value than separate T1 lines for voice and data. By actively managing the available bandwidth, a SIP trunk makes unused bandwidth available for Internet service while ensuring that every telephone call has the resources it needs for a high quality conversation.
Are you in the market for both telephone and business broadband service or concerned that you are paying more than you should for these two services? If so, get SIP trunking pricing and options to see if this service is right for your business.