I do not mean to pry but have you paid your bill?
The reason I ask is because around 3 or 4 months ago Verizon charged for something that I should not have been charged for (I do not remember what)
which caused a large sum to be applied to account. And the charge was put on after my paper bill was sent, so I had no idea that it was on my account... well after a few weeks passed I started getting calls from these random numbers (I think one may have been the 888888888) the first two times I answered, there was no one there. But the third time they called and I picked up someone answered and said "Hello I am with Verizon Financial Services." And we talked for about 10-15 mins, got to matter settled and no more random # calls...
Sorry to ramble, I believe it is VZW Financial Services calling for reason or another.