phone rang once. nobody there.

called once... no one at the other end

Got a call from them, no voice mail.  I read somewhere it might be Stanford Hospital, no idea why they would be calling.

this may be correct.  I recently blocked someone from contacting me.  a couple days later i started receiving phone calls from this number late in the evening. She works at Stanford Hospital.  And the business office is not open at 9pm.

Same here. On 4/2 11:25am we also received a call from this number. Rings until vm machine picks up & like all other solicitors, they hung up. Caller ID states Stanford Medctr. I know none of us have been to CA & in need of medical attention, or anyone else in our family/friends, so I don't know what business they have to call here. It's also possible that we were just a miss-dialed number? We screen our calls anyway. What I do know is that over a month ago I added our numbers to the Do Not Call List for all the good it did. Today we receive so many more unwanted calls than we ever did before.