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We study the problem of multiple packet bundling in multi-carrier cellular networks for VoIP and data traffic. In a time-slotted system such as the cdma2000 1xEV-DO downlink, part of a time-slot may not be fully utilized, if the packet sizes are small, as in the case of real-time VoIP traffic. Packet bundling can alleviate such a problem by sharing a time slot among multiple users, as proposed in the EV-DO Revision A system. A recent revision, EV-DO Revision B, enables further increased system capacity through multiple carriers. However, the efficacy of packet bundling, especially across multiple carriers, is not well understood. When packets are bundled, the packet with the lowest channel quality dictates the modulation and coding format of the entire bundle, possibly wasting significant slot space due to unnecessary coding bits for the other packets. We first present how multiple carriers, together with packet bundling, improve spectral efficiency, but lose some of that benefit in realistic channel scenarios. Then we propose an effective heuristic algorithm to effectively exploit the multi-carrier with bundling system. We consider QoS requirements as well as time-varying and user-dependent channel conditions, and then show how channel utilization can be significantly improved while keeping delays of real-time packets limited.