This might be a stupid question...but I am UA newbie. Now how do you redeem these vouchers or free tickets (or some other type of coupon) without being assessed a few for calling or seeing an agent at the airport? Can you call United.com web support and not pay a fee?

I was given a $25 dollar coupon for volunteering the other day but they didn't need anyone after all. Is this value now reduced because they can't be redeemed online??