After AT&T Blackberry Bold 9700 got unlocked, calling is disabled and got this error message: SIM TOOLKIT control ERROR, Call Barred.

There are two solutions:

1) Use 2G network instead of 3G and then calling feature is enabled, but data speed will slow from 3G to 2G.

2) This is the best solution
a. Download this link.
a-1, English Version - https://www.blackberry.com/Downloads/contactFormPreload.do?code=F55CADB97EAFF2BA1980E001B0BD9842&dl=52A7DF1FF0B06EE176F1C6F87CBCED31&step=4

a-2, East Asian Version (Korean, Japanese, Chinese) - https://www.blackberry.com/Downloads/entry.do?code=EEFC9E10EBDC4A2333B42B2DBB8F27B6


b. Install.
c. Go to C:>Program Files -> Common Files -> Research In Motion -> App Loader
d. Delete vendor.xml
e. Double click Loader.exe

And all set!
You are good to go!