For voice traffic over-the-air in LTE, persistent schedule (PS) or semi-persistent (SPS) scheduling would be the preferred method as they minimize signaling messages. In PS or SPS, resources are pre-allocated to the UE 402 at regular intervals (e.g., every 20 milliseconds). At each time slot, the UE will generally transmit an IMBE frames which are encoded in ISSI packet. In ISSI, other data streams are multiplexed with the IMBE frame and thus the packet size varies depending on its position within a super-frame. For PS or SPS, eNodeB must allocated sufficient resources to support the largest packet that. Therefore, there is spare capacity when the packet is not of the largest size. The exemplary embodiments specify ways to use spare capacity to transfer data.