I bought an unlocked Xperia SP in Brasil last year. Today I live in Missouri, United States and I'm having data connection problems with my device from Brazil. Since I arrived here, I only got EDGE data connection. I have tried two different SIM cards from different american companies, such as Ultra and T-Mobile. Now I'm with T-Mobile Pre-Paid Plan and I still have the same issue.
After some research, I found out that this problem can be some frequency incompatibility between brazilian and american devices.
I would like to know more information about it and try to solve my problem. I can not stay on EDGE anymore, is so slow...
Anyone has a solution?
Thank you all so much!