Yep. Apparently so.
At least they should already know who his contacts are, when he called them, how long they spoke, etc.
If he ever calls anybody. I know plenty of people that never actually phone anybody on their smartphones, it’s just not that useful a feature for them. And they aren’t even paranoid types, if you’re paranoid (like the level of understandable paranoia a terrorist might have) you can use apps like skype to make “phone calls” that completely bypass your providers switchboard and therefore records. Same with texting, there’s lots of texting website out there for legitimate use that have other uses for those obfuscating their trail.