It is a practical problem for traffic engineers to determine the proper number of Channel Element(CE)s in the base station that are required to support given offered traffic loads. In [1, Chap. 10], Kim properly deals with this problem, however, the analytic method proposed in the reference requires tedious calculation for computing call blocking probability, especially when the system supports multiple sectors and multiple frequency allocation bands. In this paper we propose an approximate analysis method reducing the exponential complexity of the old method[1] down to the linear complexity. Further the approximated results provide only a few percent difference from the exact value, which is practically useful.