A design approach is offered for individual tariffs for mass customized mobile service products, whereby operators can determine their contract acceptance rules to guarantee with a set probability their minimum profit and risk levels. It uses realistic improvements to earlier reported negotiation algorithms [1], and a full operator operational model including infrastructure and content acquisition. Value at risk and profit are analyzed when a random user has consistent characteristics to a survey group, so that risk and profits are pooled. This analysis is necessary to give the supplier business guarantees to enter individual tariff agreements. A full numerical case is given for a class of mobile service.