AT&T FREE MESSAGE: Mobile line xxx-xxx-xxxx (my phone number) has consented to share phone location

Multiple messages arrive at night saying "AT&T FREE MESSAGE: Notice; Mobile line xxx-xxx-xxxx (my phone number) has consented to share phone location or other subscriber, account, and device data with third parties. Thank you for choosing AT&T."

I asked my IT Dept. at work, and they say the messages originate in Russia.  It is some form of hacking.  How do I make it stop?  I do not have an AT&T account.