Pair-bonding is a technique that bonds, or connects, two pair of unshielded twisted pair copper wire (UTP) so that they behave as one cable with twice the bandwidth. Most homes have two pair already installed from the early days of analog telephony. The second pair is generally used to bring in a second telephone line.
It stands to reason that if pair-bonding will work with DSL signals to residential customers, then it should also work for business lines. Indeed it does. Pair-bonding is a common technique used to increase a T1 point to point or dedicated Internet service connection from 1.5 Mbps to 3 Mbps. But pair bonding doesn't have to stop there. You can bond 3 T1 lines together for 4.5 Mbps, 4 T1s give you 6 Mbps, and so on up to 10 or 12 Mbps as a practical limit. These higher order options are often available, since businesses are generally wired with many more copper pairs than residences.
So why not just go with FTTP or Fiber To The Premises for business locations instead of bonding pairs of copper. Can't you get even higher bandwidths that way? That's usually the case. Ethernet over fiber generally starts at 10 Mbps. Fast Ethernet at 100 Mbps is more common. Gigabit Ethernet is often available using the same fiber connection.
The reason to chose one technology over the other is availability. Fiber optic connections are widely available in major downtown metropolitan areas with many large office buildings. As you get farther afield, fiber availability diminishes. The cost of trenching new fiber has to be justified by a large number of potential customers in the area. If your building is lit for Ethernet, or one nearby is, Ethernet over fiber optic cable is likely to be your lowest cost per Mbps solution.
Even if fiber hasn't made it to your business park or smaller downtown area, it's comforting to know that it is possible to expand your business bandwidth by using pair-bonded T1 lines. T1 services is available most everywhere you'd locate a business. Find out how much bandwidth is available to your business location so you can meet your business expansion needs.