The law states that to disseminate on-hold copyright music on phone lines, you need a half-yearly or annual subscription to SIAE [the Italian Society of Authors and Publishers], which protects author copyright.

The annual SIAE subscription costs the following:

up to 10 phone lines .. Euro 101.95 + VAT
from 11 to 20 phone lines .. Euro 203.89 + VAT
from 21 to 50 phone lines .. Euro 293.23 + VAT

over 50 phone lines .. Euro 293.23 + Euro 53.30 for each additional 20 lines

To subscribe, you need to go to your local SIAE office. You can locate the full list of offices by clicking on this link.