[Users] a router error

Hi all I use d-link 704P router. When i want to make a call, signalisation is good, but, when the client is hang up, i have voice to the client which is connect in the D-link LAN and the other client has no voice. My server has a public IP. When i'm find the log of the router, i see these messages: unallowed access from 192.168.0.53:to 66.249.93.104:protocol=6 rule=3(by firewall) 192.168.0.53, is the adress of the client behind the d-link lan, the client which has voice and cannot transmit it! what means theses messages? how can i solve the router problem to make my calls? please help best regards! Serge