There are a couple of ways to combine the capacities of T1 lines to effectively make a bigger digital line. Some routers offer a feature called load sharing or load balancing. They act like traffic cops to keep two or more T1 lines equally loaded with packets.
A more standardized approach is called inverse multiplexing or loop bonding. In multiplexing, the bit streams from a number of different sources are combined into one transmission line. Inverse multiplexing, or IMUX, divides traffic from a single bit stream among multiple transmission lines.
Bonding sounds a bit like gluing a bunch of T1 lines together, which effectively it is. Bonding is also an acronym for an industry standards group, the Bandwidth On Demand INteroperability Group. You can get dual bonded T1 which gives you 3 Mbps, triple bonded T1 which is 4.5 Mbps, quad bonded T1 for 6 Mbps, and sextuple bonded T1 for 9 Mbps. Above 6 bonded T1 lines it becomes cost effective to order a full T3 circuit.
What are bonded lines used for? A typical application is Internet service for an apartment complex, subdivision or wireless ISP. You might start out with a single T1 line as an Internet service backbone until there are enough subscribers to require, and pay for, additional bandwidth. Then you can bond in a second T1 for growth. Another good use for bonded T1 lines is transmission of very high quality audio or video signals that exceed the 1.5 Mbps bandwidth of a single T1 line but don't justify ordering T3 service.
You can check the latest prices for bonded T1 service here.
