This number is already associated with an Apple ID? What does this mean?

Because Apple wants to provide iMessage service, it will associate the mobile phone number with the AppleID, indicating that this calling card has been inserted on other iPhones before. But it doesn't affect your use.

IMessage is an instant messaging software launched by Apple, which can send short messages, videos and so on. , with good security. Different from the SMS/MMS service of operators, users only need the data support of WiFi or cellular data network to complete communication.

On March 10, 2020, according to MacRumors, Apple is testing new features of iMessage, including mentioning "@" and withdrawing messages. These features may be released in iOS 14 as soon as possible.

May 2020 1 1 According to foreign media reports, a patent application document published by the US Patent and Trademark Office (PTO) shows that Apple may add some new functions to iMessages, the instant messaging software that comes with the iOS system, including re-editing sent messages.

Exchange text, photos and videos:

With iMessage, you can send and receive messages with any Mac user who uses iPad, iPhone, iPod touch or Mountain Lion, as well as send photos, videos, location information and contact information. If you have more than one Apple device, iMessage can keep an uninterrupted conversation on all devices.

And can send text messages, photos and videos to other mobile phones through the cellular network. You can even send text messages with Siri. Just say "Tell Xiaoli I'm on my way" and Siri will write and send a message.