Soldato
Well you 'can' use it with no CSC, you may find some services looking for settings and it generally acting up. Personally I would set one, XEU.
CSC = Customer Specification Configuration.
The CSC defines all the default bits (default language, time format, emergency numbers) network APNs and branding if there is any.
To set the CSC type *#272*imei# (your imei), this will show you the CSCs available. If you select one it WILL factory reset the phone.
All I have on mine is DBT?