We will be taking I-10 to SR57 as we have to make at stop in Upland. So which CHP offices handle those areas?Here:
At California Border Red -"Indio" This is a very long stretch of I-10 covered by one channel and dispatched by Indio.
"About" West of I-10 and 91 Split Turquoise - San Bernardino Identifies as "Inland"
At the Riverside & Orange County Line Purple-"Santa Ana"
At the 57 and 91 interchange Gray-"Santa Ana"
Plug in the Blue frequencies for each Division such as Inland, Border, also write down each Area Office number; the first one, two, or three digits of the call sign are for each respective office radio identifier. Beat numbers are all over the place.
Most Border and the Inland frquencies are repeated so, no need to plug in the moble. Indio is not repeated so you want to plug in the mobile side of the Red channel. Good luck; have a great trip.