Marshall-Mosby’s complaint alleged that CRI’s dunning letter was confusing. Under Walker, her complaint was thus legally sufficient and survives a motion to dismiss under Rule 12(b)(6). The district court improperly dismissed Marshall-Mosby’s complaint under Rule 12(b)(6), and we will reverse and remand for further proceedings. Without having raised the statute of limitations in district court, CRI invoked for the first time in its appellee’s brief the statute of limitations as an affirmative defense with respect to MarshallMosby’s claims against John Does 1-10. Despite CRI’s contrary assertions, the statute of limitations provision in the FDCPA is not a jurisdictional restriction. See Central States, Southeast & Southwest Areas Pension Fund v. Navco, 3 F.3d 167, 173 (7th Cir.1993) (<HOLDING>). As such, CRI cannot raise on appeal its
holding that absent an applicable federal statute of limitations state statutes of limitations should be applied in  301 cases if they are not in conflict with federal policy holding that oneyear limitations periods under sections 2244 and 2255 are virtually identical holding that limitations periods are tolled regardless of why the district court denied certification holding that periods of limitations in federal statutes are universally regarded as nonjurisdictional holding that time limits in title vii are not jurisdictional but are instead like statutes of limitations