Yeah, if they push back too much the Saudis would most likely just outright ban the entire service.

VoIP traffic is UDP, and will always be very easy to identify. We barely have functional circumvention strategies for higher-latency traffic types, so building a circumvention strategy for traffic like realtime voice with ultra low-latency requirements is a tall order. Honestly getting VoIP to work well in the best possible network scenarios is enough of a challenge.

I assume that higher latency communication like WhatsApp's push-to-talk "voice notes" works just fine in SA though.