I like 'em really pithy (surprise!). if you can give them the repeat menu option I would go with Flatlander's, but winnow out even more words; to wit:

Welcome to [name] manufacturing. You may enter an extension number at any time.

to reach the sales department, press 2
for accounting, press 4
for shipping, press 5
for a directory organized by first(??) name, press 7

If you need further assistance, press zero or stay on the line.

Thank you for calling [name] manufacturing.