VM LG Optimus Elite dropping calls

I use Virgin Mobile for my Cell phone
(Have for over 10yrs) have a had a few problems mostly when I try to swap phones but nothing major. Until the last month all of a sudden my calls are being dropped some where between the call coming or going out to as much as 2mins into the call. It doesn't matter if I sit in one place or if I'm moving around. it will tell me the service is gone. now I check the service strength before answering because I do live in mountains when I check I have 5+bars all green (LG Optimus Elite) 3g showing as soon as I pick up or place the call the bars will go white and drop to Maybe 2 bars. I have talked the to Customer service people at VM and they tell me that they are upgrading the network and this happens sometimes. I have family members whom also have VM phones and they are not having this problems and at least 1 has the same phone as I do. My question; is it possible that the network updates can only effect 1 person and not the others, even if using the same type of phone?