I have the VX6100 with USCellular. My menu lets me only choose between "home only, automatic A, and automatic B". I don't have the option in mine to program it to "analog only" like some other brands do. I have seen it several times, switch between analog and the 1X digital. Never had any trouble with mine anyhow.
That worked. I was able to force analog or the other modes with no problem. This is with Verizon.
The reason I wanted to do this is that I get a very weak digital signal at work and a better analog signal, so the phone automatically uses analog. In order to check my text messages, I need digital, and even the weak digital signal is sufficient for me to retrieve text messages.