Pearl in Paraguay

Hi, I'm currently living in Paraguay and recently got an unlocked Pearl from TigerDirect.com. I am using it with a Paraguayan carrier called Personal. I had an LG unlocked quadband phone before and it worked perfectly, but for some reason my Pearl only seems to work at night. Usually it has "Data connection refused" instead of my carrier name, and "edge" underneath the signal indicator instead of GMS. During the day it will immediately say "call failed" and hang up. Has anyone encountered a similar problem or know of anything I could try to correct this problem? Is it possibly my carrier? Any help appreciated, thank you.