iPhone 12
Image credit by “apple.com”

Leaked Apple Frequently Asked Questions – At least for now – if the iPhone 12 series owner uses a dual SIM, both lines will drop to 4G and 5G will not be supported.

All four iPhone 12 models support 5G, and all four devices are capable of using the dual SIM feature to provide two phone lines on the same device. However, a new leak claims that Apple has warned carriers that users will not be able to achieve 5G speeds on their two lines.

“When using two lines in dual SIM mode, 5G data is not supported on any line, it returns to 4G LTE,” Apple said in a carrier statement. “Users will only have 5G access if they use ESIM only and are on a carrier and service plan with 5G support.”

The leak came from a user on Reddit, who later posted a screenshot of the document. He or she stated that “an update will come in 2020 [which will enable 5G when using dual SIM mode”.

SS of Apple's reported carrier information document
Image Credit by “Reddit

Updated information was reported from the “Internal Training Document” section and was not copied at the leaker.

If these additional details are correct, then iPhone 12 Series dual SIM users will need to disable their SIM or ISIM to access 5G data until Apple releases an update.

Apple did not publicly comment or update its supporting documents at the time of writing to reflect this claim. The Reddit Post and its consequences were first discovered by Mac Rumors.

Analysts outside the US are concerned that Apple may not fully support the MM Wave 5G in the iPhone 12 series.