After re-reading your post - disregard what I said about DISA.
The real answer is - "maybe".
If you have a PC there on site that you can control remotely, you may be able to use UCE or, if you can find it, YA Lite didn't require a software license originally so you could just install in and control any phone. I used to freak a few people out by using YA Light to make their phone dial from their desk. That was kinda fun.
Ralph