Looking for panic button solution for our office w/possibili

I'm looking for a solution and I'm curious if anyone has ever come across one?

This is for our small office / business. It should do this:

- Small "panic"-type button that an office manager can click/hit covertly. (I want to stress that this is not for 911-type emergencies. So we don't need a capability to place a silent 911 call. This is for the situation when a (female) office manager gets a (male) customer that stays in for too long, or a similar non-emergency situation. In this case if we get this message someone will come out and "assist" her in handling such a "prolonged" visit.)

- Ideally this setup should be able to send out text messages to a group of people. It'd be awesome if we could customize text for such a message.

- Also it would be nice if such system could be plugged in, so that we didn't have to deal with batteries.

Simple GSM dialler, wired triggers send text or pre-recorded voice messages to groups of target phones.

http://www.gjd.co.uk/products/speech-diallers/gsm-communicator-gjd710