I suggest jumping off the tower and killing yourself. Seriously, it shows up in the screen that you died. There's your "shout".
If it doesn't yield results, go to orbit and come back down. Hopefully you get a new instance of the tower and can kill yourself again for notice.
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or go to menu see all that's in tower. annnnnd send invites. unless it's someone with the name of stickyhands69. ewww.