You can't link a cell phone to a hunt group. Here's something to try...
Create a Call Routing Announcement (CRA) that times out to the hunt group. Use that CRA as the Voice Mail station in the DEE Associated Destinations field. Not sure if it will work, but test to see if the DEE stations ring, then the call routes to the hunt group when the timer expires.
If that works, create a second CRA that times out to the mailbox. Use that as the Recall destination for the hunt group.
If it works, incoming calls will ring the DEE stations, ring the hunt group, then go to voice mail.