I have a 3300 with a PRI, I have been over The ARS with a fine tooth comb and can't figure out what I am missing, I can make all of my calls, local, long distance everything works fine. I can not dial 0 to get an operator out on the PRI. I dial 8+1+ anything it works fine, I dial 8+ any 7 digits and it works fine, if I dial 8+0 I hang and then go to an invalid on the display and a fast busy. The PRI carrier sees my request for operator assited call on the D-Channel but no digit 0 comes out of the switch. What am I missing