John,
I’m old school and not easily offended, you are very thoughtful my friend.

The ultimate problem is by setting up the day time voice messages G/I (general mailbox) to be delivered to an extension mapped button as opposed to an off-premises phone number you will no longer have access to F551 through the ESI System Administrator 1.2.14.29 software.

You will not be able to make F551 additions or changes through the ESI System Administrator 1.2.14.29 software (as it will crash) unless you remove the extension delivery F551 through the phone first.