Thoughts on deployment model

Hello all,

I am about to deploy Asterisk in my company and wondered if I could get some thoughts on the deployment model I will be utilising.

My aim is to use one server for one purpose; for example one Asterisk server for call processing, one Asterisk server for our contact centre, one Asterisk server for voicemail and another server for IM and Presence. I have a Cisco Voice background where this deployment model is used frequently and allows for no single point of failure as each server will have an alternative route for calls to traverse in case of failure, obviously you can have HA redundancy to mitigate this anyway.

I wonder if my deployment model will be extremely convoluted or do you guys deploy something very similar?