I believe what you're saying is that you want calls to come to a "virtual" extension (270), immediately ring a different extension (221), but return to VM for first ext i(279) f unanswered?
Create a PHANTOM EXTENSION 270. Create a mailbox for 270. Create a SYSTEM FORWARDING PATH, and have 221 as first DESTINATION, VOICE MAIL (usually 2500) as second DESTINATION. In your ext 270, FORWARDING PATHS choose the new SYSTEM FORWARDING PATH just created, and flag STATION-IMMEDIATE in the list of parameters,
Now when a call enters it will go to 270, follow SYS FWD to 221...if busy or no answer it will go to VM and remember it's a message for 270.
Hint: if you want it to ring longer at 221, just enter 221 in more positions on the SYS FWD path, so maybe 221 - 221 - 2500.