[Users] Integrating the Openser for VoiceMail and PBX with Asterisk, For Account

Hi Users, I'm new to Asterisk programming , I'm in working the Voip Technologies by using the OpenSER for my call routing process and Radius For AAA. But in Asterisk i need it for only PBX and VoiceMail, For Account I'm using the Openser + Radius . Main My doubt is that, For Call Routing my using the OpenSER. every thing is fine and Good ..

But i need the Voicemail , it forword to the Asterisk Server, that . Is the Openser takes the Accounting part or Asterisk it Take place ....

Who did the Database know the User had a voicemail in his voice mail Box... That Databases i need How ?

Please Help me .... And Mainly Excuse me in English