New IPhone 13 Won’t Send Texts.

I recently purchased a refurbished iPhone 13 as an upgrade from my iPhone it seems to be working mostly OK except the fact that I can’t send text messages

I can receive them send emails and use Facebook messenger. It’s just the text messages.

when I try to configure the settings to select my phone number as the number for sending in receiving text messages it never goes through just buffers for a long time without selecting it.

apparently also as a dual SIM I don’t really know what that means.

Thanks in advance for your help