Do you have a balance in the account to cover the roaming charges? Although I would think that you'd be charged in and out, not just out.
I thought the same thing about having money in the account. I added money to the account to and it still didn't help. It's very frustrating as I've talked to Verizon support and they have no idea.
Try one of these network refreshes:
Basic phone: *228
Smartphone: Remove SIM card, power off, Reinsert SIM, power on. (If you can't get to the SIM without removing battery, just power off first and then remove SIM, wait a min, reinsert SIM, and power on.