Why can't dual-card mobile phones switch numbers to send text messages?

1. Open the settings of the mobile phone, find the dual-card settings and click Open;

2. Find the default dial card in the opened dual-card setting option, and click Open;

3. Check the "Default Dialing Card" option as "Do not set";

4. Open the Messages App again, click the blue color in the upper right corner, and select a new message (some mobile phones click "+"to create a new message, depending on the specific function of the mobile phone);

5. In the "New Information" page that pops up, enter the "Recipient" to be sent, and a "Major Number/Minor Number" button will appear below;

6. Click this button, select the card to switch in the menu below, and you can switch numbers to send short messages.

Dual-card mobile phone can't change the number when sending text messages. It may be that the default dial card is set on the mobile phone, so it is always the primary card or the secondary card when sending text messages. Just check that the default dial card is not set in the dual-card setting of the mobile phone, and then switch the number when sending a short message using the short message function.