So... if you read the post immediately after this one....I spent all day fighting "call denied" messages on a system because calls were restricted after hours and I didn't know it. It is an option under "night service." I think (maybe someone can add to this) if you password protect your night service button, phones are restricted from outgoing calls unless you add them to an "excluded list". I am not sure that the password protection is what causes the sets to be restricted, but in the programming sheets they were on the same form. So...try password protecting the night service button, and then dial 9 from an MLX phone and see if the display says "call denied".