Is there a new GMC phone number to get the unlock code for the anti theft lock on the radio? The one listed on the internet is disconnected

What is your question?

My battery died on my 96 Impala SS and the radio is locked. There was a phone number to call and give a 6 digit code for the radio. I have called the number listed 1-800-537-5140 and it is disconnected. Is there a new number to get the unlock code? Is there a way to unlock the anti theft device without paying the dealer? the dealer wants me to bring the car in.