This letter proposes a novel constraint-based 3G network planning model and a novel hybrid approach for optimizing the 3G network planning problem. Computational results show that the model and the approach are more efficient than the mathematical model and the existing heuristics. Optimal solutions are always obtained for small and medium sized problems. For larger sized problems, the final results are on average within 5.77%-7.48% of the lower bounds. The proposed hybrid approach can be an efficient tool for tackling a wide range of combinatorial NP-hard problems.