Verizon says "Growing Pains" responsible for LTE outages14
Once the problems were corrected, the bugs did not return but customers were unable to access the LTE pipeline (and even the 3G pipeline in some cases) even though both networks were up and running. One thing that Verizon has started doing is segmenting the 4G network into smaller areas so that if there is a problem in one area, the whole LTE network isn't dragged down.
Haberman says Verizon's goal is to make sure that it's 4G network has the same high level of service that Big Red's 3G network offers. He says, "We're not there yet, but we'll get there." Verizon touts its network as being the most reliable and when you put yourself out like that, you need to deliver. Considering the large number of activations that Verizon had to deal with over the last few weeks, it sure doesn't look good when a new 4G customer turns on his phone and the network is down. If there is one good thing that came out of the three outages, it is that Verizon was able to figure out what caused them, which should allow the carrier to install the proper safeguards to prevent the same exact conditions from repeating.
source: GigaOm via Phonescoop