Methods are provided that optimize Voice over Adaptive Multi-user channels on One Slot (VAMOS) communications by recognizing that up to four independent communications are located on the same device, and assigning them to sub-channels of the same VAMOS channel. A VAMOS-capable multi-SIM wireless device such as a dual-SIM dual active (DSDA) device may have up to four simultaneous active calls on the same access network. When assigned to the same VAMOS channel, the up to four active calls may be merged to all use the same radio on the device.