How to switch Apple's dual-card sending number?

Apple's mobile phone supports adding dual cards, and users can change cards and send messages when using them:

1. Open the SMS editing dialog box and click the sender number above.

2. Click on the phone number to switch the phone number to send a short message.

If it is a new message, just enter the recipient information and click the calling card button to switch.

The principle of dual card dual standby of Apple mobile phone;

Judging from the current technical realization, there are several dual-card schemes for Apple mobile phones on the market. One is composed of two chipsets, that is, two sets of baseband chips, RF chips and memory system are installed in the mobile phone, which is equivalent to putting two complete mobile phone motherboards in the same mobile phone case.

This implementation can support two SIM cards to work at the same time, and there is no need to turn on and off the phone again, but the problem is that its cost is almost twice that of ordinary mobile phones, and its power consumption is often twice that of ordinary mobile phones. Many bulky dual-card dual-standby mobile phones on the market are using this scheme.

One is to add an analog switch to the traditional mobile phone chipset and manually switch the network. The latter is usually the realization of "dual card single standby" mobile phone, but later some enterprises use it in dual standby mobile phones, which is prone to problems such as incompatibility with various SIM cards and immature control software, and the call drop rate is very high.