My assumption is based on the differences between the Charge (non-HR) and the Alta I was given after 4 Charge replacements. The Alta does text alerts but doesn'

My assumption is based on the differences between the Charge (non-HR) and the Alta I was given after 4 Charge replacements. The Alta does text alerts but doesn't do stair counting. Assuming the latter only needs an accelerometer there isn't anything obvious in the hardware that might other be missing to make it impossible.