Solved my problem after 8 hours of troubleshooting! After the 17.2.1 update, my iPhone 14 Pro Max would not send or receive calls and got hot from accelerated battery drain. First AppleCare walked me through hardware diagnostics, network resets, backups and restores but the problem persisted. Next, Verizon helped me with a new eSIM, but the problem continued. Next, I focused on my company's corporate software, because I was intrigued by the VPN discussion in this forum. While I don't use a VPN, my iPhone is managed by my company's installation of Microsoft InTune, which I noticed (Settings:General:VPN & Device Mgmt) had a signing certificate (IOSProfileSigning.manage.microsoft.us) that had expired December 12, 2023. To test this theory, I removed this Management software and my phone's cellular calls worked perfectly again! So for the final steps, I worked with my company's IT department to reinstall the Management software, which has an updated IOS signing certificate, and the phone is now back to normal. Sharing in case others find my painful tech journey useful.
