Called and said they were from United Healthcare on behalf of AT&T. Had my name. Wanted to inform me of other services available through plan. Said in order to speak to a nurse about these services,  I would need to provide my address and date of birth. I told her, "you should have that info on file."  She said she did, but needed me to confirm. I replied, "you read it to me and I will confirm it."  She said due to HIPPA laws she couldn't.  I blocked number as it didn't come up as United Healthcare when I Googled it.