The information is owned by AT&T. They can be forced to hand it over to government warrant/subpoena. Or, they can choose to freely offer it (more likely sell it) to the government.
We can pass laws (and have such as with medical records) that even though the information is owned by <company> they can not use it/reveal it/etc because it is violation of privacy.
But we haven't done that.
Also, one thing many people don't remember is that the constitution/bill or rights restricts the government. It does not restrict private enterprises. Corporations are not required to protect your free speech, right to not be unlawfully searched, or any other right granted by the constitution.
We can pass laws (and have such as with medical records) that even though the information is owned by <company> they can not use it/reveal it/etc because it is violation of privacy.
But we haven't done that.
Also, one thing many people don't remember is that the constitution/bill or rights restricts the government. It does not restrict private enterprises. Corporations are not required to protect your free speech, right to not be unlawfully searched, or any other right granted by the constitution.