Finally figured this out. The door lock (it wasn’t the doorbell after all) is connected to a central hub device using z-wave which is some proprietary IoT 900Mhz technology. The home hub has a functioning cellular connection, which I was totally unaware of. The installer never mentioned it. The cellular connection is notifying their servers that the battery is low. Apple push notifications are still being delivered to their iOS app on my phone, even though I’m not logged in, since the systems are independent. nostr:note1qr82s20nr5yqv2f3z5gaa7ggr09d3rs4hz4whf4yvlp0cdcu6hrqaz2n4s