The Sacto and Bay Area systems were treated separately. A Sacto user could not use it here in the B.A., and vice-versa.
Now, according to their website, it appears it is now treated as one big service area. What they did before is arbitrarily draw a line half way between the two areas. They have always had coverage along the 90 miles of #80 between here and Sacto - users would just get cut off as they cross that half way point.

...mike