I've used skype, teamspeak, steam, etc. for audio chats. If you're gaming then teamspeak is probably your best bet. It's a little tricky to setup but you can bind the mic button to a key or leave it set to "always on" or to turn on when your voice is detected and it's pretty stable and allows for large groups to talk at once.
Skype is pretty good too. It's not perfect but it can do group chats with small groups. You can also screen share too if you want to show someone what you're doing on screen (won't work on some steam games though). It's pretty user friendly and easy to setup. Btw, if you have a webcam, make sure it's set how you want (on/off) before initiating a call. I think on laptops it defaults to on.