@deanooo: Unfortunately the function to block texts with no number on the Messages app is not available. If you open the text, and you can only see a recycle bin symbol in the top right corner, as opposed to the 3 vertical dots, then then sender cannot be added to the Block List. In this instance, I recommend reaching out to your network provider to see if anything can be done from their side to block the messages. Alternatively, as per the advice above, you could try another messaging app to see if the option is available there. I apologise for any inconvenience this might cause you.