Operators behind glass terminals shouldn't throw insults
Only one thing to say and that is receiver sensitivity. Contrary to the belief of the omniscient keyboard jockeys, sometimes it is that socratic paradox of the "Cable Monkey" that saves the day. The de facto expert by being physically present at the errant installation or having the presence and presence of mind to think about the problem before dispatching the entire spares for EMEA to site and hauling everyman upto the Prime Minister onto conference calls.
At the basis of telecommunication is electromagnetic radiation and as dear Claude Shannon defined in his information systems model there is a sender and a receiver that the quality of the message is dependent on the noise in that information system. What seemed to elude many a keyboard-bound technical expert was that the signal of the message if too great at the receiver can be as detrimental as the signal being too low at the receiver. That is where the monkey magic is introduced and an attenuators are added to the media to ensure that the signals are within the operating limits for the system and presto the system works with an air-gap in the optical path or an added 50 metres of cable.
In my varied career this provided the egg for the faces of many of the smart arse tyrants of the TTY and problem managers. The fact is we are all blinded by our roles to the wisdom concealed by other people's trades. It is after all practice and knowing what we are doing; leaving that can be done to those best placed to do it.