Never miss a birthday
Birthdays are easy to intend and easy to miss. A calendar entry only helps if you open the calendar. A text at breakfast is harder to ignore.
Set it once a year
Create a yearly reminder with the person's name and what you want to do — call, text, or mail a card. RemindViaText will fire every year at the same local time.
The day-of problem
A week-ahead reminder is useful for gifts. A morning-of reminder is useful for the message. You can keep one active reminder on the free plan; upgrade if you want a list of people.