The objective of this study is threefold: (1) to review the evolution of mobile networks in 3GPP standards; (2) to present the evolution of the Quality of Service (QoS) of the 3GPP mobile family, from GSM to LTE; (3) to present the QoS frameworks, characteristics and attributes of each technology. In the last two decades, 3GPP mobile networks have been evolving from GSM to LTE providing end-users with improved QoS. However, all these networks are still in use up to the present time. Users moving from a coverage area served by one technology to another area covered by a different system would have to perform vertical handovers impacting their established QoS and affecting the performance of their applications. All the QoS mechanisms as well as their theoretical performance as a whole are reviewed. However, in commercial networks, it is proposed that QoS attributes and data measurements be continuously performed in order for operators to set more realistic users' expectations and provide more practical information for application developments. © Maxwell Scientific Organization, 2014.