This is a rather surprising u-turn given the amount of flack Blizzard received when they mentioned their intention to make it a premium service. Players were not happy with this shift to having to pay more to be able to play with friends. Blizard has released an FAQ to address players questions:
Q: How do I invite Real ID friends to a Real ID Party?
A: Inviting a Real ID friend to a Real ID Party is simple. Just open up your friends list to see which Real ID friends are online. Click on the Plus button to send an invitation to a Real ID friend to join your group. You can continue to add Real ID friends to your party until the group is complete. If you cannot complete the group with Real ID friends, you are free to join the Dungeon Finder to fill in the missing roles.
Q: Does a player need to have Real ID enabled to accept a Real ID group invite?
A: Yes, a player must have Real ID enabled, and both players must be Real ID friends to accept or initiate Real ID party invitations.
Q: Can a party leader invite a mix of Real ID friends, character-level friends, guildmates, or random players to the same party?
A: A party leader can invite any combination of Real ID friends from any realm, guildmates from the same realm, or other characters from the same realm to the same party. If the party leader isnt able to fill up the entire party, the Dungeon Finder can fill in the missing roles.
Q: Can I invite someone who is not a Real ID friend?
A: You can only invite members to a party if they are on your Real ID friends list or if they are on the same realm as you are.
Q: Can I invite a friend of a Real ID friend?
A: No, you can only invite your own Real ID friends the party.
Q. Are you considering expanding the system to work with raids, Battlegrounds, Arenas, or to allow cross-faction play?
A: We're always looking into ways to improve features like this to make it more convenient for real-life friends to play together. However, we don't have any further announcements to share at this time.
However, they hint that future additions to this particular service might well involve handing over money: