working fine for me with the most up to date version of Hangouts...
also to note, on my AT&T HTC One M8 (that I'm using currently, I left the OnePlus One at home today),
under APN type I have:
not sure if that's needed or what is on my OnePlus One, but I'll check tonight.
iPhone 6 (64GB, Space Gray) - Pre-Ordered
Sony Xperia Z2 (16GB, White)
HTC One M8 (32GB, Glacial Silver)
iPad rMini (16GB, Space Gray)
LG G3 (32GB, White) <- returned. laggy OS but I loved the hardware
OnePlus One (64GB, Sandstone Gray) <- sold on Swappa
Nexus 5 (16GB, Black) <- sold on Swappa
Galaxy S5 <- laggy POS and TW sucks