It's not that big of a deal, you just enter the keycodes in programming under "Software Keys", then change your card to PRI under "Hardware". You will need to know line coding info and protocol type from the telco. As for the down time the customer experiences, depends on how quickly you get this done and telco. If my memory serves me right, you also have to go to lines 1-23 and configure for E&M Winkstart.