I know this thread is old, but I am having a problem with the same issue.
I have SP1 set to Callcentric right now, and if I dial **1**275*xxxxxx, once I hit the first * after the 1, I get an immediate error. Why won't it take any more stars? What do I need to change in the digit rules to allow me to enter the **275* or any other 3digit code after ** when I want to use a different provider? I would like to just be able to dial this manually with any 800 number of my choosing, so setting a speed dial would not work. I want it to recognize the **275*, and then accept the next 11 digits at face value, and send all of that to callcentric.