Telecom operators have to manage their resources efficiently to minimize the congestion in theirrntelecommunication network. In Ethiopia, heterogeneous wireless networking technologies such asrnGSM, UMTS, CDMA and LTE are being used to provide wireless access for both voice and datarnservices. In big cities, the densely populated areas like town centres, shopping centres and trainrnstations may have coverage of multiple wireless networks. Traditional Radio Access Technologyrn(RAT) selection algorithms are mainly based on the â€˜Always Best Connectedâ€™ paradigm whereby thernmobile nodes are always directed towards the available network which has the strongest signal.rnHence a large number of mobile users may be connected to the more common UMTS while the otherrnnetworks like GSM and CDMA would be underutilised, thereby creating an unbalanced load acrossrnthese different wireless networks. This high variation among the load across different co-locatedrnnetworks may cause congestion on overloaded network leading to high call blocking and callrndropping probabilities. This can be alleviated by moving mobile users from heavily loaded networksrnto least loaded networks.rnrn This thesis presents a load levelling algorithms which is used for load balancing in heterogeneousrnwireless networks. The technique comprises of load-aware RAT selection techniques and networkrnload balancing mechanism. Different attributes like load distribution in all wireless networks, packetrndrops, throughput at mobile nodes and network utilization have been observed to evaluate therneffects of load balancing using different scenarios. The simulation results indicate that with loadrnbalancing the performance efficiency improves as the overloaded situation is avoided by loadrnbalancing. The load change value is 11% for the sites in the focus area. This shows that the voice callrnhas been pushed to the neighbour 2G cell and congestion in 3G network has been improved.