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For better capacity and higher availability, present day third generation (3G) wireless systems based on the code division multiple access(CDMA) technology are evolving to operate on multiple carriers (frequencies) spread over multiple bands. In order to provide better quality of service, the 3GB (3rd generation and beyond) systems need to distribute calls equitably to different carriers on different base-stations accessible to the mobiles irrespective of the bands or carriers on which those mobiles initiated their calls. However, there is a risk of call failure when a call originated on a carrier in a band is migrated to another carrier in a different band, particularly because of the differences in the radio coverage of the base-stations operating in different bands. This paper presents a class of methods that offer equal robustness against call failures and varying degrees of call distribution effectiveness. For call distribution, these methods employ an enhanced carrier capacity measure (ECM) proposed in this paper. ECM augments the gross capacities of the carriers (to house calls) with pre-configured biases specific to the mobile users. We develop here an intuitively appealing distribution-effectiveness measure based on the ECM for comparing the methods. Relative performances of the proposed methods with respect to call failure rate and distribution effectiveness are established by means of simulation results for calls originating anywhere in the cell coverage area as well as calls originating exclusively near the cell boundaries. The latter results help to study the effect of mobility on the performances of the algorithms.