In checking for my own purposes how Segment populates `network.carrier`, I found that the instance property used in https://github.com/segmentio/analytics-ios/blob/e35f1c984687f3216810145c8f1a8360fad20a72/Segment/Internal/SEGUtils.m#L368 - that is, `subscriberCellularProvider` - has been deprecated. See documentation at https://developer.apple.com/documentation/coretelephony/cttelephonynetworkinfo/1616900-subscribercellularprovider (Apple recommends using `serviceSubscriberCellularProviders` instead).