The sim card is mainly for the 4G service. I once did the sim card pull, but it in wrong and fried the card. I had 3G where I used to have 4G. I took the phone to a Verizon store and told them what I did. They replaced the card at no charger.
AFAIK, the bars are for the phone signal only and nothing to do with the data signal.
When I get kicked off 4G at house(I get bad signal) I have - 65 downstairs I get about - 90 its probably an issue with ur phone
Clearing the cache has helped... I'm not constantly dropping 3g anymore. 3G dBm levels are still backwards though...:confused: Anyone else care to share 3G dBm Levels?
Settings > about phone > status > network type and strength