Originally Posted by Ryan Silva
My phone(Galaxy Gio) appears to have signal(3G Signal all the lines are full) but I can't call or message anyone, nor vice-versa. I thought that it was the SIM card at first. I've tried other two sim cards that were working on my other phone, the same problem. It's some weird issue with the phone.Also when I plug in the USB cable the phone keeps connecting and disconnecting giving low battery alert.
It seems to be a ROM-related issue.
Which ROM are you using?
If it's a custom ROM, try to backup it through CWM, and then wiping for a factory reset. If it still fails, try to switch to another ROM or directly to stock one, to test if there it works.
Let me know.