Drew Seeley, however, provided the singing voice for Troy Bolton in the first movie (High School Musical). Zac Efron's singing voice was not considered strong enough for the role, so Seeley was brought in to sing Troy's parts.
This decision was not made public until after the first film was released, and it was a bit of a controversy at the time. However, Seeley did not appear in any of the films, only providing his voice.