on the slt can you dial an internal ext, could be barred, or try a key set to see if that works.

to have it pick up line 3 look at hot line and set pickup dial as 83 or 9 and program co out for that extension and enable only co 3

on message lamp problem from that phone dial in to the mailbox enter option 6 then option 2 message waiting lamp status and make sure it is enabled

“I have not failed. I've just found 10,000 ways that won't work.”