"Maxxi Alice 150" is just an option offered for TIM prepaid SIMs. To activate it you need to send an SMS containing "PRO MAXXIALICE150" to 4916.
Also you have to configure the correct access point (APN) either in the Nokia PC Suite, which is ibox.tim.it
If internet access has worked with your TIM SIM before and now you can't even place phone calls, you may have burned your credit by accessing the web without activating the data option. So check your balance by sending "SALDO MAXXIALICE100" to 4916. If it's consumed, you need to recharge € 30 in order to have enough credit to activate the desired option "Alice Maxxi 150".
Btw "Alice Maxxi 150" is only valid in the evening, on weekends and bank holidays. Check
http://prepaid-wireless-internet-acc...y+-+TIM?t=anon for more information on TIM's data options.