There are Cat 5 network cables in the office going from some rooms to some other rooms through the walls and the ceiling.
The office belonged to another company in the past, which means that there is no guarantee that nobody installed a tracking device in the walls, or that the cable doesn't go to a different office in the building, where it can be tampered with.
Is there anything which can be done using hardware or software on both sides of the cable to ensure that the cable was not tampered with (in other words, that this is indeed a single cable, and not two ones connected through a device such as a switch)? Or the actual, physical inspection is the only way?
To reduce the scope of the question, I'm talking about ordinary tampering by introducing a basic switch which can track what gets through it (and possibly redirect the traffic to another port for inspection, as most switches are able to do). Of course, this excludes military-grade devices which are specifically designed to not only trace the communication, but also resist any attempt to identify them.