Quick google search of number gave this:
http://receivefreesms.com/+19702968172.phtml
Ctrl+f "17747664670":
Quote
17747664670 2 months ago My Wallet Authentication Code: 1D26A - https://blockchain.info/wallet/71c08ed3-b92e-4fe1-b1fc-557c8611ae7a
Interesting. Then directly above that, same wallet ID and different auth code for it, but sent to +19702968172 from a different #:
+15179925059 2 months ago My Wallet Authentication Code: 8874B - https://blockchain.info/wallet/71c08ed3-b92e-4fe1-b1fc-557c8611ae7a
I thought I had BC.I SMS payment notifications disabled, since I've been receiving payments for months without one...
I just refreshed my BC.I app and the last payment in the All tab was days before 2/23/16 and not a match for the amount. None of my BTC is missing, since every address in there is watch-only and never saw the private keys.
Maybe I had a test wallet for a private key posted on reddit or something.
