Used to have 3 bars, now one or none

[DBLedet]

We have had Verizon wireless for over 10 years and have always had 3 to 4 bars of signal on any of our phones.  In the past 6 months the signal strength has dropped to 1 or none and I can't make calls out. We recently got new phones and the signal strength has not changed.

Why has the signal strength dropped so low that we can no longer make calls? 

A tower went up last year that was just on the other side of our neighbor. It appears to have ATT antennas on it because my work phone now gets full power all the time when before it only got 2 bars.  

If my signal strength doesn't get better so that I can make calls I will have no choice but to move all of our phones and tablets to ATT just to get service.

I hope you can provide some information to keep us on Verizon.