Personal Line
"This is Jin. Leave your name, number and message after the beep and I'll get back to you when I can."
Business Line
[I'll put in the actual Japanese once I get back so I can actually see the hiragana/kanji. :|]
"You've reached Kazama Jin, CEO of the Mishima Zaibatsu. State your name, number and a brief message after the tone and I will get back to you as soon as possible."