Emmanuelle Vaugier, playing Mia, is, in reality, a very accomplished singer in her own right. Her atrocious singing in this episode can safely be put down to her terrific acting abilities.
Episode title spoken by Alan, to Charlie.
Charlie asks Mia, "Are you still at 696-336-725?". Even if you dial a 1 first, this is a nonexistent number as there isn't a fourth number at the end.