Thanks for the feedback this far. It is very appreciated.

I have worked my way through the programming sheets and have figured out that things are a bit different than I first thought...

1. On all extensions except 10 and 11, pressing speaker will not get intercom or an outside line. The user needs to press the line they want.

2. Any extension can call 10 and 11, but no other extension will ring on an intercom call (they show as busy, even though they are on-hook). CO lines ring through immediately.

3. Programs 81, 84, and 87 are now on for all extensions for troubleshooting.

4. Program 32 is now set to 101 for all extensions.

5. COS program 30 is now set the same for all sets - that is 1,3,5 and 7 are on, all other lights are off.

I'm sure this is some simple program, I just can't figure out what has changed through. If all else fails, I am trying to get a set of marked up programming sheets from this business's corporate IT - hopefully they have them.