First check whether the number you entered is correct. Is everything in order on your end? There could be several reasons why you’re still not able to choose your carrier.
To start with, there is a possibility we do not (yet!) support your carrier or country. If you can’t find your country of choice in the dropdown-menu, this means that the recharge you want is not an option yet. Could you find the right country but not the desired carrier at the following step? Then we, unfortunately do not (yet!) support this carrier.
Another possibility is that our system can’t link your number to the right carrier. If you’re sure about your carrier, you can also change it yourself or change which carrier is selected.