Hi Mike, the voice nos. for the S700 (and most Yam KB's) are available here:
http://www.yamaha.co.jp/manual/english/index.php

Type PSR S700 into the Search box, then select Data List against PSR900/S700.
You'll get a pdf file and voices are amongst the first pages after the index. Make sure you get into the section for S700, the first voice pages are for the S900.

John