Yes, but I would need to go back to the switch and that is a good 15 min walk. I need the link light to be on the loopback plug
Maybe I should be more clear about the situation I am having...
I am the only IT guy for a 300 room hotel, 600 terminals (including the guest terminals in each room), so I cannot be there all the time. In many cases, since this is a historic hotel, things are not as easy as they would be in a home or new building. When other contractors come in to place new phone lines or data lines, or electrical, or rats chew through wires or whatever, I need to make sure there is connectivity to the switch closets for all these terminals. If there are some sort of other problems, that isn't too much of the concern right now, I just need to make sure the jacks in the event rooms and guest rooms that go to the patch panels in the switch rooms are live.
Now a loopback plug with the LED would be perfect, since all I need to do is plug a patch cable into it, then the other end into the jack. If the light turns on, then that is enough for this project. If the light doesn't turn on, then I know there is a problem.
Walking back and forth between rooms and switch closest, just even in the event rooms would take forever. Right now I borrow a guy from the in house repair guys, but often they are running around making repairs to air conditioners or whatever is broke in the hotel.
While walking around with a switch and battery wired to it is a possiblity, I just need the link light, and it would be much easier walking around with a patch cable with a loopback plug that has the ability to light when connected to a live connection on the end. If I need to build it fine, but I can't seem to find anything exactly like that. Always close, but no cigar, or it would stilll require two people.