Tool to test analog phone line connection quality

Question

An ancillary job of mine is to support an analog phone line for our credit card machine. From time to time AT&T changes out hardware in the core which causes the machine's modem to not connect over the phone line.

Testing the line by plugging in an analog phone is not rigorous enough. Often the phone will have a dial tone and place calls, but there is too much noise for the modem.

I am looking for a hardware tool I can plug into the RJ-11 jack which will evaluate the line quality. I have a budget of up to a couple hundred dollars if necessary. I need to know if the line quality is degraded and unable to carry a modem connection.

I appreciate any recommendations of a tool to do this job.

Answer 1

Some older modems could perform line testing. You could simply get a pair of modems, and attempt to make a call, then see what link speed you get. Your credit card machine probably just has a standard modem in it.

http://web.archive.org/web/20110907062746/http://www.scn.org/help/linenoise.html

Answer 2

I don't know what tool to buy (nor am I sure if Server Fault is the right place to ask - perhaps EEE?), so I'll suggest this:

If you don't have a cabling contractor that you regularly use, make contact with one. Once you have a cabling contractor, explain your situation, and see what they suggest (or how much they will charge to do the job for you).