Anyone here a Correctional officer in Canada?

I will be going to school soon to help me become a Correctional Officer, but what I am really interested in is becoming one of the tower guards in a max. security prison. I was just wondering if those tower guards were once regular CX's or if you have to take a completely different path to becoming a tower guard? I do not mind doing regular Corrections stuff as I think that will be a very interesting job as well. Thanks for any info other Correctional officers can provide, or even a tower guard if theres one on here! Thanks!