Hello my friends!
As soon as you introduce your first Exchange Server 2013 in your organization you first action may be trying to logon on ECP/EAC to get access however since your administrator account still on Exchange Server 2010/2007 you will be redirected to the ECP instead of the new EAC (if you don’t see anything you need to establish the transition first).
Read more at source: http://www.andersonpatricio.ca/?p=1372
Cheers,
Anderson Patricio
http://www.andersonpatricio.ca
http://www.andersonpatricio.org (Portuguese)
Twitter: @apatricio