How exactly does the US have access to French phone records, to the extent they can record conversations, and full content of SMS messages? I would presume all

How exactly does the US have access to French phone records, to the extent they can record conversations, and full content of SMS messages? I would presume all those systems would reside in France, or the EU at the very least? So who is providing them this information, or given them unfettered access to them? And why has nobody noticed until now?