I have a Galaxy A22 and it is not allowing me to send text messages to certain numbers which I have been able to before. It's only some people's numbers but not others. My contract with the service provider allows me to send as many texts as I like. I have checked for any issues with signal, WiFi, and also switched between SMS and MMS but still can't resolve it. This first started about 3 weeks ago and since then I haven't been able to send 1 texts message.
Sounds like you may have a problem sending to other networks from yours, I use EE and in the past had troubles like this, but not for a long time, I would give you network a call and report it, but it could be there networks ??