More likely, in the context of Android modems or IMS stacks, "v1280" refers to a specific software version or a proprietary profile implemented by a hardware vendor (such as Qualcomm, MediaTek, or Samsung). Modem software is updated constantly to fix bugs and improve handovers. A log entry reading "mo-voicecall-v1280" likely indicates that the call was processed using a specific logic set (Version 1280) of the voice call handling algorithm.
While specific manufacturer documentation is often proprietary, the suffix in telecommunications strings generally points to one of three things: 1. Codec Bitrate and Sampling mo-voicecall-v1280