For those of you who are interested in joining the cross-faction (Alliance and Horde), as well as all Battlenet games, via YOUR BATTLENET ID, the link is below. AGAIN, this uses your BATTLENET ID! So if you have a problem using that do not join that community. 
I have not seen that the actual Battlenet ID shows anywhere in the community.
https://blizzard.com/invite/VjKr9p3F3xA
***NOTE - How to Join
- Click the link which will open your Battlnet launcher.
- Click Groups+ on the upper left-hand side.
- Choose the second tab “Join Group.”
- Paste your code into the box that will pop up.
- WoW will assign a channel number for that community
- The community will be added on your left.
- There is a “Add to Chat Window” option below the chat line/bar. You need to click that and choose General. This allows any chat to show up in your chat window.
If you are using Identity 2, these are the codes to use below. Simply type them into the chat line.
/id on
/id main (Insert your forum name or main character name)
/id enable guild
To enable the communities:
- Go into your Identity 2 settings
- Choose the Communities tab
- From the Add Community Drop Dow Menu, choose the community you wish to add.
- Make sure the Enable Community box is checked
- Make sure the Enable Channel box is checked
- Please note that Old Timers Guild Combined Battlenet has 2 channels.