OK, here's one that might even give Ed some trouble. Just opened my recently purchased 601. It has 3 K400E cards, a 401B and a K403A, two empty slots and one unmarked ITT card manuf. 3-85. My understanding was the 601 included the intercom so is the 401B an extra intercom? Isn't the K403A a buffer for MOH? And what could the unmarked card be? It is in the first slot from the top and doesn't look like any KTU card I've seen before. Some help, gentlemen?
