Call establishment through fake ip address

Hi everyone, is possible establish a voip call from SIP INVITE message carried by a udp packet with fake ip address? Is more likely that the replies will be sent to the fake address, so the call cannot establish communication this way. Please let me know if I’m wrong.

Thanks in Advance

A couple of assumptions I’m making:

  • “fake IP address” => a private IP address

  • “udp packet with fake IP address” => the payload in the UDP packet may reference private IP addresses that are not the same as the source IP address

In which case, the answer is “yes, this happens a lot in SIP.” It is quite common for private IP addresses to be conveyed in various SIP headers. When needed, there are multiple ways to solve this problem; Asterisk provides several in both chan_sip and res_pjsip. The most common is to simply ignore the private IP address and send requests/responses to the source IP address instead.