The American version of sprint 4s has a built-in card sticker. Now the system ios7.0.4 uses a mobile card, which has a signal, but it can't send text messages or open a mobile phone. Ask for help.

The question about sending short messages is to set the number of the short message center. The steps are as follows:

1, query SMS center number: enter *#5005*7672# in the dialing interface, and then press dial to get SMS center number;

2. Modify the SMS center number: dial *5005*7672*+ SMS center number # (please remember to enter "+"for SMS center number here), which should be modifiable;

Regarding the problem of cellular, you should first check the settings of cellular mobile data, as shown in the figure. Remember, SMS and cellular settings will not take effect until you restart. Thank you.