Iphone4s can't send text messages, only receive them. What should I do?

1. Turn on phone settings-Messages-Send and receive MMS, and then turn on the switch to send and receive SMS again.

2. Enter the restore point for restoring network settings, and click Settings-Open General-Click Restore.

3. Enter Settings-General-Network and start data roaming.

4. Turn on the dial of the mobile phone. Enter * 5005 * 7672 *+8613800abc500 # in the dialing interface. Abc is the local area code (for example, Shenzhen is 755), then press the dial key,+is the long press 0 key.

5. Check whether the phone bill is available. If there is no phone bill, you can't send text messages.