An ACS can do that. Connect station port to CO port, then use the "hotline" programming to autodial that extension when the extension goes off hook. Works well for dial-less customer service phones and such.

It also works with offsite numbers. Put the off-site number in as speed dial 80 and set it to hotline, and it'll go offhook and dial the number when picked up. Works well with things like 24 hour bank customer service lines when the branch is closed.