Both T1 and T3 are part of the same family of telephone industry technical standards called T-Carrier. This technology was invented after WWII when it started making sense to use digital carriers to replace analog carrier telephony. What carrier telephony does is let one pair of telephone wires transport multiple conversations. Analog implementations set up a multiplexed arrangement much like radio stations on the AM or FM band. Each phone call was loaded into its own channel on the carrier system. At the far end, they were demultiplexed to extract them into individual telephone lines.
Analog carrier telephony had its issues. One was that the lines tended to get noisy and crosstalk between channels over long distances. If you are old enough to remember long distance services in, say, the 1960s, you remember hearing hiss and garbled conversations in the background. Once digital carriers were deployed, all that noise and crosstalk disappeared. A long distance call is every bit as quiet as a local call.
As technology progressed, the need for long distance digital lines to carry computer data became important. T-Carrier technology was already in place to digitize phone conversations and transport them as bits instead of varying voltages and currents. The logical move was to use these digital line services to also carry computer bits and bytes. The demand for digital circuits really took off when the Internet was commercialized in the 1990’s. Since the lowest speed standard T-Carrier is T1 at 1.5 Mbps, it was T1 that became the choice for business connectivity.
Most businesses were fine starting with T1 private lines and dedicated Internet access. Some needed more bandwidth immediately and others outgrew their T1 bandwidth. The next step up is T3. However, T3 is not 3x T1 bandwidth as you might suspect. It is 28x the bandwidth when you round off the actual bandwidth numbers. A T3 line runs at 45 Mbps.
T1 and T3 differ by more than just line speed. T1 is provisioned over ordinary twisted pair telco wiring like you’d have for multiple line telephone service. There really isn’t a T3 line that runs from your business to the telco central office. That’s more of a colloquialism. T3 is delivered on two small diameter coaxial cables with BNC connectors. That interface has a relatively short maximum run, so it is mostly used within the building or for a short run from the curb to the demarcation point in the building. The actual T3 “line” to the service provider is most likely a fiber optic run.
The terms T3 and DS3 are used interchangeably, but there is a fine line of difference. T3 is a physical line. DS3 is a data service that runs on T3. DS3 can also be multiplexed onto a OC-3 or other fiber optic service and be transported that way. That may sound like splitting hairs, and for many purposes it is, but it can be a problem when go you to order service. For instance, if you order a T3 line you’ll be getting DS3 if it is available. That will depend on having fiber optic service running nearby. If not, you probably won’t be able to get T3 or DS3 at all.
Does that mean that you are stuck with T1 bandwidth? No, not necessarily. Technology advances since the invention of T-Carrier have created more options. The first is a process called bonding that combines the bandwidth of two or more T1 lines. A double bonded T1 circuit delivers 3 Mbps. Triple bonding takes you up to 4.5 Mbps, and so on up to the practical limit of 10 or 12 Mbps. That’s not T3 capacity, of course, but it meets the needs of many companies that don’t need the full 45 Mbps T3 bandwidth.
Another advance is called Ethernet over Copper. This is the familiar LAN protocol extended to run over telecom lines. Ethernet over Copper (EoC) also uses multiple twisted pair copper wiring, so it is easy to connect as long as the proper terminal equipment is in place at your central office. EoC is distance sensitive, but if you are within a few miles of the central office you can get bandwidths of 2 to 45 Mbps over copper. What’s more, Ethernet over Copper bandwidth is less expensive than T-Carrier on a per-Mbps basis. You may well get T3 bandwidth levels for as little as half the cost, depending on your location.
Is your company tight on bandwidth and considering an upgrade to your T1 line service? If so, get a complete set of competitive quotes for bonded T1, Ethernet over Copper and T3 service options specific to your business location.