Many T1 lines are installed without proper testing and configuration. It is important for the provider and the customer to balance risks arising out of this situation, not only to avoid expenses on testing equipment, but also to make the T1 line error free. T1 line testing is a slightly complicated process for a technical amateur. You need to know the technical aspects of Internet thoroughly to connect the T1 lines and get it working properly. But there are a few simple procedures that could be followed to test the working condition of aT1 line, or to find out what has gone wrong during a breakdown.

During a break down, the first step is to determine whether the problem is with your PC or the T1 line. If you get a message saying the computer is using a saved version of your default home page when you open your Internet explorer, there is definitely something wrong with the T1 line. The next step is to check if the CSU/DSU, the router and hub are plugged into the telephone line and their lights are blinking. If they are, switch them on and off alternately three or four times. This will solve most kinds of T1 line problems. Once you identify the problem, the best way and the most popular one to test signal problems on T1 cables is the Bit Error Rate (BER) test. After configuring each T1 line for the test, you should let it run from one minute to 240 hours. This will give an error statistics base in the T1 line.

You can also use Cisco or other loopback testing devices to isolate the problem of the T1 serial link. These can be software loopbacks or hardware plug-in loopbacks. Another way of running a BER test is to configure a remote testing tool which will transfer data simultaneously with the test pattern. Once the problem is identified using loopbacks in two different directions, they can be rectified by resetting multiplexers at either ends of the T1 line.