We consider the decentralized bandwidth/rate allocation problem in unicast service provisioning with strategic users. We present a mechanism/game form which possesses the following properties when the users' utilities are concave: 1) It implements in Nash equilibria the solution of the corresponding centralized rate allocation problem in unicast service provisioning. 2) It is individually rational. 3) It is budget-balanced at all Nash equilibria of the game induced by the mechanism/game form as well as off equilibrium. When the users' utilities are quasi-concave the mechanism possesses properties 2) and 3) stated above. Moreover, every Nash equilibrium of the game induced by the proposed mechanism results in a Walrasian equilibrium.