I have an iPhone 15 Pro Max on version 18.5 and Webex app on 45.5.0 (10727) and everything work ok when connected to WiFi but when on cellular data I can make & receive calls but no one can be heard. When ringing out I don't hear it ringing.
I had the same issue on the iPhone 12 and there was a known issue to do with IPv4/IPv6 hence the reason I upgraded and all was working ok until the last week.
All works ok on cellular data on an Android device and with another network provider sim.
Anyone know which direction I can point my network provider in as they insist that it's not an issue their end but testing shows otherwise. Any help with this greatfully received!