Received 4 calls from this number, 3 of which were on the same day. I finally answered the 3rd call and it was a guy doing a health and wellness survey from OU Medical. Stated he wasn't selling anything. I hung up and blocked the number once he identified himself.
No caller ID, no message, not in my contact list = I AM NOT GOING TO ANSWER. If it's legit, they can leave a message. It's my phone for my use, not theirs.
The call was from OU Family Medicine Center calling with an appointment reminder. The 405-271-#### are part of the OU Health Campus and everything within it.