When does my SMS sending capacity reset?

There isn't a reset date.  Clinic SMS sending capacity is based on the number of message segments sent on a rolling 30-day period.  At the moment that we attempt to send an SMS message, we check to see how many SMS message segments your clinic has sent within the last 30 days.  As long as it's less than your sending capacity, we send it.  There is no "reset date" in this way of calculation since it's always done in real-time, at the time of delivery.