Mobile service providers (MoSPs) emerge, propelled by ubiquitous availability of mobile devices and wireless communication infrastructures. MoSPs' customers satisfaction and consequently their revenues, largely depend on the quality of service (QoS) offered by wireless network providers (WNPs) at a particular location and time of a mobile service usage. This chapter presents a novel business method for the MoSP's QoS-assurance process. The method incorporates a location- and time-based QoS-predictions service facilitating the improvement of the WNP's selection process. We introduce and analyse business viability of QoSIS.net, an enterprise that provides the QoS-predictions service to MoSPs or directly to its customers (i.e. in B2B or B2C settings). QoSIS.net provides highly accurate QoS-predictions based on collaborative-sharing of QoS-information by its users. We argue that this business method can improve the MoSP's QoS-assurance process and consequently may increase its revenues, while creating revenues for QoSIS.net.