The present invention relates to a method and apparatus for controlling a connection transfer in a cellular network having at least two systems, such as a GSM system and a WCDMA system. Based on a load determination, a service-based inter-system or inter-frequency handover of the connection to another system or to another carrier of the same system is initiated if the determined is below a threshold and service priorities are indicating it. If it exceeds the threshold, an additional load-based inter-system or inter-frequency handover can be initiated. If the load of the target cell is not known, a load estimation based on a learning process can be used to derive a probability of success of an interfrequency or inter-system handover, which may be used for deciding on the initiation of the inter-system handover. The learning process may be performed by evaluating preceding interfrequency or inter-system handovers to the target cell or preceding interfrequency or inter-system handovers from the target cell. Thereby, users can be shared between different radio access technologies or systems or between different carriers of one system to thereby improve network capacity and quality of service for both systems and carriers. Furthermore, unnecessary inter-system handovers can be prevented in case the load of the target cell of the other system is not known.