At very popular events like music festivals or soccer games, base stations for mobile devices might be congested and, thus, are not able serving all mobile devices in their coverage. Thus, some mobile devices might be without connectivity to a mobile network operator. Specifically, they may be disconnected from the on-line services they are using regularly. In such a situation we envision that a connected mobile device is sharing its connection into the network with others. In order to make connection sharing attractive, the users offering their connections to others are remunerated thus getting an incentive. The problems arising are (1) the negotiation of a contract between the parties and (2) the gathering of evidences that the contract has been fulfilled. We solve these problems by a protocol that employs an authentication scheme that works without access to an infrastructure, supports contract negotiation between mutually authenticated actors, and that generates evidences so that actors can prove that the agreed contractual obligations have been fulfilled. It is described how the risk of loosing incentives is managed.