When I'm in one place, why do the bars on my phone change?

[Digital_is_the_new_Analog]

@Learjeff

Is CDMA used for 3 & 4G? I thought it was just 2G.

@Turble

Yes. My phone is CDMA. At home, in a little valley with only one tower available, it sometimes connects at 2G, sometimes 3G, and out and about it sometimes goes 4G LTE.

More specifically - The 3G and 4G may be capable of falling back to 2G, which could be CDMA. 3G is going to be WCDMA, and 4G is going to be LTE.

Give or take carrier and vendor definitions, which are about as meaningful as the number of bars being discussed.