Where do doctors get my insurance information from?

When I go to see my doctor, the front office staff look me up on their computers and find my insurance information. Where does it come from?

Normally I would expect that they go to a website from my insurer and get the details. But now I know this not to be the case.

I changed health insurance at the start of the year. When I presented my new insurance card at the doctor’s office in January, they typed into their computers and promptly told me that I was still covered under the old insurance, because their system told them so. I had to call the old insurer and request a Termination of Coverage document for the doctor’s office to agree.

Another time a doctor’s office refused to agree that I had already met my deductible because their system said so. I asked them to call the number of the back of my insurance card but they refused. Again I had to call and request a letter stating that the deductible was met.

So where exactly do doctor’s offices get their health insurance information from?