atcomsystems.ca/forum Forums TDM Business Telephone Systems Nortel Telephones & Systems adding a 5th trunk to a 616 with only 7408 phones

Good Morning! I am trying to add a fifth co to in a doctors office that only has 7408 phones. I easily added a fourth co, but the fifth button down where I want to add the trunk is also the Heading button when in programming. I believe it is a v. 2. Any help would be greatly appreciated Thank you.