I don't remember if my phone number is somehow tied to sending push notifications or not.
At this point, I am always able to successfully send and receive outbound push notifications if i setContactKey to my phone number. If I setContactKey to any other GUID or random non-empty, non-null value, I do not receive push notification events.
What could be amiss? Where can I change something so that contactKey can be anything else other than my phone number? At this point, outbound push notifications to all users is acceptable.