
The Importance of a SIP Aware Firewall for the VoIP-Dependent Enterprise - cahitakin19
http://www.mushroomnetworks.com/blog/2015/12/15/the-importance-of-a-sip-aware-firewall-for-the-voip-dependent-enterprise/
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tshtf
_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-
traff...](https://www.onsip.com/blog/in-depth-verizon-blocks-sip-traffic-
using-alg)

