Migrating to a new Asterisk Server Box

Hi Guys,
Currently I´m new to the world of Asterisk, I have a old box runing a callcenter with 2 campaign of 15 guys total with pretty decent specs for the amount of users (Core i5, 8GB Mem, 500GB hd, etc)
This campaing do inbound and outbound calls, using a callcentrix with 4 trunks, runing CentOS, and Asterisk V.11 But I´ve been informed that I need to get a new box since they´re growing from 300 up to 500 seats (agents). I wonder if you guys can suggest and help me out what will be best option (box) to get.

Thanks a bunch Guy,

Rgds,

Elliot :0)

For a callcenter installation I should consider minimum of 8gbyte ram and definitely upgradable in case of extra needs.
Consider ssd disks especially if you are using the same box for the autodialer software. Logging and writing to mysql would be a bottleneck for you if you have a slow drive. Related to the cpu keep in mind more ghz is better than cores.