Whats is the best IP phone in a noisy factory. And is it possible to connect a extern flashing light or horn at an IP phone
Just to add a note to the great tips from Tim. (+5 points for your good work here Tim :)
Have a look at this "cool" IP Phone built for this type of environment;
From Cisco partner;
Coleman Technologies, Inc. - EnviroXtreme
For the noise issue we use the Stinger Ringer (Model 196) from Dees Communications. You will need an Analog port off a VG or ATA (with the IP Phone Directory Number) to power this device.This thing is super loud and works well for us. Here is an excerpt from the documentation;
The Stinger Ringer cuts through the noise of any environment with a powerful 110 dBA. Its intense signal is transmitted in all directions and reaches every corner of an industrial location or home.
The Stinger 90, Model 196, operates directly from Central Office power. It has a modular plug that connects right into a standard telephone wall jack. This unit is equipped with a three position volume switch (hi - med - low).
Here is a link to the actual doc:
Hope this helps!