Enter Conference from Outbound Call

We have a FreePBX system that is used to send a recorded message during an emergency that tells the callee that they need to join a conference bridge. The message contains the conference bridge number to call and the conference bridge ID to dial when they call in.

What we want to be able to do is allow the user to enter a star code or # plus code during the call to be connected back to the proper conference bridge they need to be in. Is there a way to do this? Either with a module like Conference Call Pro (using the Conference IVR option if needed) or another method in performing this action?

Basically when they answer the call the message will just have “Press X at any time to join the conference now”. and once they press the code it will connect them to the bridge.

I believe I found a suggestion during my searching over the Internet but I forgot to bookmark the page and I can’t seem to find it now that I’m actually looking for it (of course). So any ideas or suggestions are welcome and very appreciated!