service providers can block or enable traffic from whatever numbers they wish.
I once had a vodafone with access to the Government’s special telecoms network – it wasn’t even a work one (I was then a Civil Servant), for some reason it just came with this enabled! (not much actual use as I could dial work anyway direct and it didn’t count towards your free minutes)
anyone sending malicious texts is committing a criminal offence and Orange/France Télécom is legally obliged to take action if you report it..
