Most SIP aware firewalls utilize SIP Application Level Gateway (ALG) architecture. Verizon Wireless does this in the US, and it completely breaks most SIP appl

Most SIP aware firewalls utilize SIP Application Level Gateway (ALG) architecture. Verizon Wireless does this in the US, and it completely breaks most SIP applications, unless you connect to your server over a VPN: https://www.onsip.com/blog/in-depth-verizon-blocks-sip-traffic-using-alg https://www.onsip.com/blog/in-depth-verizon-blocks-sip-traff...