How does Apple set the number of SMS center?

How to set the number of Apple SMS Center: enter * 5005 * 7672 *+861380ABCD 500 # in the dialing interface (long press 0 to enter+key), pause for a few seconds, and then press the "Dial" key lightly. After the setting is completed, you will see the prompt "Service Center Address Set Successfully, No Address", which will take effect after restarting. ABCD is the local area code. If the area code is three digits, the last digit is filled with 0. (Example: Shanghai 02 1, and the number of SMS center is+8613800210500; Zhengzhou, Henan, 037 1, the number of SMS center is +86 1380037 1500).