According to an email sent out by Libera Il Voip:
Starting on May 1st, access to hosted PBX-like services (which for the moment only include VoXalot and PBXes) will be blocked from LIV.
The reason is that the LIV server seems to be sending/receiving a disproportianate amount of calls (they note hours and hours of calls) to/from PBXes and VoXalot on behalf of a handful of users.
Given that they operate on a Volunteer/Donation basis they find that this activity by a few users is increasing their resource usage.
For more see:
Informazione sul "blocco delle interconnessioni tra liv e i centralini" page 2
This is just a heads up for anyone using them in conjuction with VoXalot that things may not work after May 1st.
On a personal note: I wish they could limit usage from these two servers without blocking it altogether...