It will be considered a repossession and when the dealer sells it again, if they don't get enough to cover your loan amount plus their costs, you will still be liable for the difference. You might get the dealer to agree to not come after you for the additional amount but get everything in writing. Best if you try to sell it yourself.
When you call the dealer to surrender the car, you will lose some amount of money from your credit since you have already used the car. It is advisable to find another way of paying for the vehicle before surrendering it.