I tried with iPlayingCards. Downloaded on two devices on the same wifi network and it worked. I could get audio/mic working through both devices. Then I put one device to cellular and it didn't work. Then, I tried to get a friend on a totally separate wifi network to download the app and try. They were able to get the audio/mic working on two devices on their network but when we tried connecting together (two devices on different wifi networks) the audio and mic did not work.I suspect voicechat only works when the devices are on the same network, but anyone with evidence to suggest otherwise, I'd appreciate hearing from you.