Don't rush to try iOS 12.1's dual-SIM support if you're a customer of our parent company Verizon. PCMag has learned that the current software drops iPhone XS, XS Max and XR users down to CDMA (that is, the 2G network) if you activate another carrier on the eSIM and use your Verizon SIM card for the secondary line while in the US. This won't hurt if you're roaming abroad, but it's crippling for domestic use: You'll lose anything resembling fast data, and even basic coverage will shrink, given that 30 percent of Verizon's cell sites are LTE only. Accordingly, Verizon has decided it would rather decline to activate eSIMs for now than make users suffer when they rely on the company for a second line.
In a statement, Verizon said it would only activate iPhone eSIMs once it was "confident" it could provide full service on both the primary and secondary lines. It doesn't expect this situation to last forever though. After talking with Apple, Verizon expected the issue to be "resolved quickly" (presumably through a software update) and to start activating eSIMs "before the end of the year."
This is bound to be frustrating, especially since other US carriers don't appear to have the same challenges. With that said, it's not completely surprising that you might have to wait. Apple's eSIM-based approach to dual-SIM support is new for the industry at large, and that hasn't exactly given providers much time to address network-specific problems.
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