Mobile Phone to Loud Hailer auto answer -- HELP!!

[gpullen]

Hi,

Im new to these forums so please go easy on me!!

Ive been asked to set something up for a friend, an add-on to his CCTV setup. Basically he wants to be able to dial into his building via mobile phone, and be able to talk over loudspeaker.... either to people breaking in... or to tell his staff to get back to work i guess!!

I need to set this up quickly, and dont have great electrical knowledge. I was hoping someone on here would be able to point me in the right direction!!

So far my idea is.... a cheap pay as u go mobile phone, connected to an amplifier and then to a loudspeaker. It is all going to be mounted outside thus needs to be weather proof.

Please have a look at the attatched image in large view, for my quick mock up.

What i need to know is, can i simply take the headset audio out feed straight into an amp? Do i need a pre-amp?

Is it safe to place the mobile inside my suggested power supplys casing? Will it cause interference or fire hazard?

Many thanks to anyone who can help!!

 

[UNG]

Some of the speech diallers used in the security industry can listen in on the site as well as talk to the site to frighten intruders