Some coastal cell towers can reach up to 40 miles, *BUT* your cellphone latches onto the nearest tower, which once at sea and they switch it on will be Regatta's own tower, leaving you paying Cellular At Sea's piratical rates.
"WiFi calling" might be an option if (1) your cellphone provider offers it, (2) your cellphone is equipped with the option and you enable it, (3) there's enough bandwidth from Regatta at the time, and (4) it's not
blocked as "streaming" (or you pay for the "WaveNet Prime" upgrade).
A caution: WiFi calling dials and rings just like normal, so if it gets de-selected by accident you're back to paying Cellular At Sea rates.
See you aboard!