Abstract-Several voice over internet protocol (VoIP) providers migrate to their services to session initiation protocol (SIP). SIP is a lightweight signaling protocol used to implement in wiled VoIP services. However, with the global spread of this service, we can see how VoIP is affected by the stealing of SIP trunk services. Thus, the VoIP Trade Company will exhaust it effort and income. Our survey shows how much SIP security is enforced when somebody cracks the SIP server, and looks for any VoIP process trunk IP to use the server as a legitimate user, or to try to harm the trunk by injecting it with a forged source code that will lead to a road map for the hacker. The latter will make it deny the server, or inject it with the SQL script effect to come with DDos attacks. Our study shows the interest of researchers and students on VoIP security. It also provides a road map between the hypotheses and implementation, particularly on how SIP is affected by the variety of attacks from the outside world and from inside the local network.