On a discretionary appeal from a class certification order under Fed. R. Civ. P. 23(f), the Court of Appeal has jurisdiction to review any issue bound up with the decision to certify the class. Thus, in this case, on a 23(f) appeal from an order certifying two nationwide TCPA classes, the Court of Appeal had jurisdiction to consider whether the district court erred in finding concluding that the defendant had waived its personal jurisdictional challenge to out-of-state class members’ claims based on Bristol-Myers Squibb Co. v. Superior Court (2017) 137 S. Ct. 1773. The decision also holds that the trial court erred in finding a waiver. At the time it could have moved to dismiss, the putative class members were not yet parties to the case, so lack of personal jurisdiction was not yet “available” to the defendant to raise as a defense to the case, so there was no waiver under Fed. R. Civ. P. 12(h). Nothing prevented the defendant from raising personal jurisdiction as an objection to certification of nationwide classes at the class certification stage.