Charm Blue Note Unicom mobile phone card slot 1 supports Unicom's 4G/3G/2G network, and card slot 2 only supports Unicom/Mobile 2G network, not telecom network. If you use a telecom mobile phone card, it is recommended to use Charm Blue Note Telecom Edition. Card slot 1 supports telecom 4G/3G/2G networks, and card slot 2 supports mobile/Unicom 2G networks.
In addition, China Unicom and China Telecom both have FDD-LTE standard, but the obtained 4G frequency bands are different, so there is no connection.
(pictured) More parameters can be found in Meizu official website/products/products/meilannote/spec.html.