Most policies have a convenient *out* in that they allow themselves to give out this data so that they can stay on the good side of the government. CPNI deals with sharing data with other private parties, not government.
FWIW, Here's what a MetroPCS's subscriber agrees to let the company do with private information when signing up for their service (basically anytime anywhere they feel it's worth it for them)...
We may disclose Personal Information, and other information about you, or your communications, where we have a good faith belief that access, use, preservation or disclosure of such information is reasonably necessary:
* to satisfy any applicable law, regulation, legal process or enforceable governmental request;
* to enforce or apply agreements, or initiate, render, bill, and collect for services and products (including to collection agencies in order to obtain payment for our products and services);
* to protect our rights or interests, or property or safety or that of others;
* in connection with claims, disputes, or litigation – in court or elsewhere;
* to protect users of our services and other carriers or providers from fraudulent, abusive, or unlawful use of, or subscription to, such services;
* to facilitate or verify the appropriate calculation of taxes, fees, or other obligations due to a local, state, or federal government; or
* in an emergency situation.