We are deploying a new VoIP system through our network. We are using Ribbon SBC 100. We also have recently deployed a new Sase Firewall on the network, Zscaler. The problem is when we turn on the Zscaler tunnel on the specific network, the SBC drops the connection. With Zscaler enabled, the “SIP/2.0 200 OK” isn’t being returned to the SBC when it sends out the OPTIONS packets. The way Zscaler works is it sends outbound traffic to Zscaler to be inspected and then returns, but with a different IP. The SBC does not recognize this traffic and therefore drops it.
The solution we were looking into is to bypass the Zscaler tunnel completely and set up a split tunnel. We are not sure how to do this though. We are using Meraki MX-100 for smaller sites and an MX-250 for larger sites. We have a GRE Cisco 891F we have to test as well.
Any help would be appreciated!