there are only three real reasons for a remote server:
1) limited bandwidth - if you have enough bandwidth available for your agents to reach the server, but not enough for 30-2000 calls from the server "to the public", you can use your bandwidth for the agent->server communication and then the remote location's bandwidth for server->public.
2) uptime - if you have no IT staff and do not want the responsibility of maintaining the server hardware or OS, a colocation facility may handle that for you. in our case we handle the hardware, the OS, and even the Vicidial software and all related. Most clients do not even want console access ... as long as the Vicidial Interface works they are happy. We offer console for those in other categories, of course.
3) physical security - a remote server cannot be removed from your office by anyone, since it is not there. There are many implications, and the result of that statement depends entirely on your view of the world. Mull it over from a few angles.