What should I do if I can't send Apple 4 by SMS?

First, open Settings-Network-Enable 3G, and then turn on data roaming.

You can fill in APN:3GNET or 3GWAP or UNINET in the cellular data network dialog box, but you can only log in after WAP is cracked.

If you are cracking WAP, iPhone.

4 General network cellular data network in setup: APN fills in 3GWAP, and user name and password are left blank.

It should be noted that in the above settings, the WAP mode is slightly more complicated, and it may not succeed according to the above settings, and the file may need to be modified, mainly due to the operator's reasons.