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.