Incorrect. They need a warrant to (legally) even collect phone call audio - they can't tap your line ahead of time, and then get a warrant when they want to listen to the recordings.

Unless you meant the metadata of who you called. But that's not the police collecting that data, but the phone company doing it voluntarily for billing purposes. If the company didn't keep those records, the police couldn't (legally) compel them to without a warrant.

I think the legal position is that only data access requires a warrant, not data retention. The in.es.ā. argues this, local police don't have that access - they buy things like location data on the private market though

Yes, that was the NSA's argument, but I'm unaware of any court buying it.

Except that it doesn't actually keep them from doing it unlawfully. As long as they believe they're acting within the law (despite being wrong) they can do it with no consequences.