Phone Sim not connecting in Router

Hi all, 

I have a smarty data sim that I was using in my Cudy 4G router, all good. As I was low on data I tried to put my smarty phone sim in the router as it has 50gb pack but it will not access the internet, I have activated the sim and reset the API but it will not connect, when I put the data sil back in it works fine again. Any ideas? 

kindest regards, Al.