[Asterisk-Users] Supervisor monitor / barge in - automatically on call setup?

[David John Walsh]

I'm aware of the legal issues surrounding my request, but any help
technically would be greatly apreciated

On site we have a fully staffed hospital and fire service (its a
temporary event for a childrens charity) and an onsite "911" number. 
If a user dials the number, they goto the emergency crew, and the use
of monitor helps to record the call - thats the easy bit

I'm in the UK, and its an offence not to pass a 999 (our 911) call out
to a 999 centre but with the sheer numbers involved, we have a few
choices, only one of which is suitable.

If a user inadvertantly dials 999 I would like to pass it to the true
999 and at the same time dial either a special phone, or all the
phones in the emergency centre.  Upon the centre answering it, it
silently monitors the call between the user and the 999 centre.  If
for whatever reason the centre needs to barge in they can, prehaps
even silencing the origninal user.

We have a 2 min response time to anywhere on site, the offical user
services have about 22, but we know and expect that in a moments panic
someone will dial the number automatically

Any assistance as to how this can be performed will be greatly apreciated.