Big problems in Brazil!

Hi,

I bought this phone about a year ago, with the idea of using it to travel with. I'll spare the past episodes, but when I arrived here in Rio de Janeiro, Brazil about 5 days ago, I went directly to a reputable place to buy a local SIM chip, since I'd had my phone unlocked before leaving the States. The carrier is called Vivo, and after they installed the chip, my phone saw the network and listed it (Vivo) on the main screen.

Everything was going well. I was able to make and receive local calls, which is exactly what I wanted to do. The only thing I was having trouble with was the Voice Mail (or Caixa Postal as they call it here). They told me I had to wait a few days and then it would activate. (Sounds strange, but Brazil's a unique place.

Then, all of a sudden this morning, I get a message whenever I try to use the phone that says "Emergency calls only" in English. The carrier Viva is no longer listed on the main screen, and I'm unable to make or receive any calls at all. When people call me, they are sent immediately to Voice Mail, which of course, I can't access.

I'm going to be down here for a month, and I absolutely need to be reachable. Can ANYONE help me with this? I would be forever in their debt. Thanks for any advice,

Nela