There are signs in my county that say "Volunteers Needed for Fire and EMS. Work for pride, not a paycheck" with a toll free number to call.
Speaking from experience (with two different squads at the same time) volunteering is tough. Not everyone has the stomach for it, is in good enough shape, or really has the time. I know I dont have the time, but I do it anyway, because i've gotten so used to not sleeping all night and seeing people at the worst moment in their lives. I know a couple people who want to do it but are scared, but it's a big jump to take, and I dont blame people for being scared - it's hard, dirty, thankless work most of the time. But I always encourage them to help in some way - be it auxiliary, fundraising, or riding on a rig. I also try to help get people applications, give tours of the ambulance and fire trucks, set up ride-a-longs, etc, so they can see what we do first hand - which often times inspires them to act.