Star2Billing provides a commercial voicemail module although still licensed under the AGPL. This can only be installed on Star2Billing certified installations for technical reasons, and is suited to the Enterprise Editions of A2Billing, especially the Enterprise
Systems, as the voicemail recordings are held in a database, lending itself to systems where there are multiple Asterisk servers installed, and also allowing room for expansion of the system.
A Voicemail interface is is also provided for the customer to allow them to download voicemails, or play them directly from the Customer Interface. The customer can also dial in and listen to their voicemail via their phone.
You should budget for €600 Euro for the installation of the voicemail system onto A2Billing. Training and limited ongoing support on the voicemail system is also included.