I am pretty sure this may not be possible. Customer has 9.1 Essential with 6 analog lines. They have asked if I could set up a key that dials a number BUT, it has to pick line one. They for some reason want to keep their third party voicemail and to retrieve message you must dial *98 from line only. I made a appearance button for line 1 and have them press it then dial *98 and it works but they asked if it could be a one touch operation.