When LASD got the contract back with MTA the contract called for MTA to pay for and LASD to build a two frequency for TSB dispatch and L-TAC. In the interim SCC pulled two of the frequencies that had countywide coverage (Investigator 1 and C-TAC3) for TSB use.
INV-1 occupied #35 on the radio/telephone monitor and became dubbed Disp 35 by dispatchers for a lack of a better term. I always referred to it as INV-1 when raising an air unit in the early days so Aero knew exactly where to switch as AERO rarely worked TSB capers at the onset.
As far as Disp 16 goes, never heard of it, but TSB/CCB should be referred to in this manner. The number in the console matrix should not matter being that Lancaster/Palmdale Disp 15 are actually on Freq 59.