Text reminders cut a nearby surgery's DNA rate by 40% — what are clinics using?

the gp surgery nearby apparently brought their dna rate down by about 40% just with a text reminder system. we're looking at something similar for our clinic but the pricing varies so wildly between providers that it's hard to know what's reasonable to pay. what do other small private clinics or wellness businesses use for automated patient reminders and what kind of rates are you paying?