Hey Guildies!
Have you checked Guild Launch Mobile App yet?
It has a Voice Chat system, which I won't use since it works with regular phone calls and for me to connect means making an international call to the US. I think the more interesting function are the notifications. I didn't link my Guild Launch account to my main email account as to avoid an overflow of incoming emails, so for me, the app is perfect to receive notifications!
/Belarkan