@ejs - That's very weird. If they can really remotely detect the type of NTE5, then that means it's distorting the upstream signal in some way, which is bad. If it's generating a return signal as a conditional response to some incoming "activate test" signal, then that would be expensive, complicated with a significant component count and would cause some insertion loss (attenuation).
Surely they mean that they just consult their records? If you've bought your own NTE5C then that would be considered naughty in any case if you replaced the existing NTE5, but you could always chain the new device off the old instead.