Better late than never, but I wanted to update you that we still have the case open with Engineering and CISCO, and it’s been about four months now. We captured packets related to this issue and were able to isolate several things. Among them, we found that the One-way Audio only occurred when placing a call on hold. Sometimes it happened quickly, but eventually, after leaving the call on hold for a few minutes, we would experience the problem. A firmware update for the phones was implemented, which allowed us to restore voice if One-way Audio occurred after recovering from hold by putting the call on hold again and then recovering it. But as we all know how users are, aside from attributing these issues to WEBEX (and that this didn’t happen with CME before...), they didn’t remember the workaround.
Anyway, about a week and a half ago, they contacted us to say that after our numerous labs, captures, and sending the exact time of the drop, they discovered that the issue was related to ICE (Interactive Connectivity Establishment). Like with other technologies (e.g., Cisco Meraki cams), ICE allows devices to attempt to communicate internally without generating traffic to the internet. However, during this negotiation/check, it seems that voice was being lost. We tested it by disabling the ICE feature in our physical phone profiles, and since then, the calls no longer drop. It’s clear that this feature helps and optimizes WAN traffic usage, but knowing how much our calls consume and that many users are using the Webex Client (not a physical phone), it seems 100% worth it to eliminate this issue by applying the mentioned workaround. Once we’re notified that the solution has been applied in new upgrades, we’ll test it, but for now, it’s working, and we’re very clear about it, given that we simulated and conducted a thorough follow-up with both CISCO and our operator, reaching the clear conclusion that the only solution was on the CISCO SIDE... Therefore, “disable ICE on the devices until further notice.”
