Is oppoa57 mobile phone dual card dual standby 4g? Why can't I send a text message to the other card when I put two cards, and then it's only 2g?

OPPO A57 mobile phone dual card dual standby is not necessarily a 4G network, which is related to the type of SIM used. If you put two cards, the other card can't send text messages, and then there will be only 2 G. It is suggested to call the customer service hotline of the communication operator to switch to manual operation, and consult the information setting in detail, especially whether the number of the information center is set incorrectly. The customer service staff will send you the specific setting parameter information. (You can also try changing a SIM card to see if the same problem will occur. )

The following is the dual-card operation instruction of OPPO A57 series mobile phones: 1. Full Netcom Edition: Mobile card can be used with Unicom card and telecom card at will, any card can be used with 4G network, and the other card is in the voice phone state of Unicom 3G network at most. 2. Mobile version: It is the 4G+ version of China Mobile, and the mobile card can be used together with Unicom card and telecom card at will. When a mobile card is combined with a non-mobile card, the default mobile card is the main card, and 2/3/4G network can be selected. Non-mobile cards can only be used as secondary cards, and only 2G voice can be used; When inserting two mobile cards or two non-mobile cards, the main card and the auxiliary card can be switched at will. The main card can be a 4G network at most, and the other card can be a Unicom 3G network voice phone at most. 3. Two telecom cards cannot be used at the same time. At the same time, one card can use the 4G network, and the other card will not be able to register for the network.