Re: Oh boy...
And if you did set a threshold, is there really a point at which you can readily set one? Is 50% packet loss on one connection among many too much? 25%?
There is a world of difference between RTCP stats for the VOIP RTP stream and the Android or IOS perception of "there is Internet". First of all, they also take into account rtt and jitter which are at least as important than loss. Second, if RTCP is implemented in full both sides are fully aware of what their counterpart thinks about the link quality.
If neither the phone, nor the Net can initiate handover based on VOIP quality assessment, then the system is completely broken to start off with.