The ptime 10 ms is not supported.
We are considering some fixes, but acording our research Chrome and FF browsers use ptime=20 with WebRTC and it seems it is not possible to chnage it.
In such case we will need to do ptime conversion between Chriome(ptime=20), FF and other WebRTC compatible browsers and your gateway(ptime 10). It’s currently not in our short-term roadmap.
Please consider usage of ptime=20 for Flashphoner peers at your IP PBX.