The very best way is to have everyone get a Skype account. It is free and it is easy to install. You can call people Skype to Skype anywhere in the world for free.
The next thing you do is have someone in the group start a chat and "invite" everyone in the mastermind group to the chat. You can have as many people as you want in it.
Now here is the key. Never close the chat and never log out of it. That way you can always check it and update yourself on what has been said. It makes things very easy.
I have several of these things going and I always have access to people I can ask questions. Can it be a distraction? Yes, but you have "Do Not Disturb" buttons and you can show yourself unavailable when you need to do something.
Try it out and see if you don't agree!