My iphone4s can't send text messages. I use Unicom 3g card.

According to your description, I suggest you try to test your Unicom card with a mobile phone that can support Unicom network. If you still can't send it, there may be something wrong with the card or package data you are currently using. It is suggested that you need to call local 100 10 for help. In addition, if you have sent a lot of short messages, it may also affect your use. If your card can be issued, there may be something wrong with your mobile phone. I suggest you try to restore your mobile phone network settings, and I suggest you go to Settings-Information Settings to check whether your settings are correct.

In addition, if your mobile phone is a foreign mobile phone with a locked version, it may not match the card sticker after the system upgrade, which will affect your use. Before using this card, you need to replace the matching card.

If it is not for the above reasons, I suggest that you need to bring your mobile phone card and mobile phone to Unicom's own business hall to help you test.