Samsung w20 15 can't send short messages without receiving them.

It is suggested to take the following steps for investigation and handling:

1. Check whether you can make a phone call, and rule out whether the phone bill is insufficient or the network signal is unstable.

2. If the call is normal, please check whether the SMS blacklist function is set.

3. Try to replace another SIM card.

4. If it is invalid, please back up the materials (contacts, pictures, etc.). ) and restore the phone to the factory settings.

If the problem still exists, I suggest you take the purchase invoice and replacement card and send your mobile phone to the nearest service center for testing.