First generation texting software.
Very annoying, because you have to click the buttons really a lot. e.g. 3 times the 2 for a C, 2 times the 3 for an E.
T9 makes texting a lot easier, although a lot of people turn off their T9 and use Multi-tap all the time.
A: My phone is giving me all these funny words!!
B: Go back to Multi-tap then, you big nerd.