An early upgrade fee and an upfront cost for a phone are slightly different.
An early upgrade fee is the cost to get out of your current contract and upgrade early, and it sounds like you don't have a fee to upgrade and can therefore upgrade free of charge.
The upfront cost for a phone is a one-off upfront charge depending on the price of the phone you choose and the monthly charge of the contract. Not all plans will have an upfront cost.
