Blackberry Storm 9530 on AT&T Congestion and other problems

[JDub1986]

Hey guys I'm new here so I'll just be brief with the problems I am having. I have an Unlocked Blackberry Storm 9530 from Verizon. I've followed the procedure for loading the generic AT&T service books to my device and I'm using the 4.7 OS. Well, the phone has been working great but now it's telling me that there is congestion when I try and make a call, my txt and MMS is still working perfectly. I'm getting really fed up with the near constant problems I have with the device. I'm just curious if anyone would possibly have a fix for the problem and if anyone knows a way that I can get service books that will work with OS 5.0?? any help would be greatly appreciated thanks!