As far as I know, there isn't a slot on any phone for cash. How do you expect to get money to Steam? Phone companies aren't banks.
I think he means that he wants to add funds to his steam wallet from his phone credit, like you can do with some web based games. The answer to this is no. However you can buy steam gift cards from stores now and then redeem the gift card to your steam wallet.
As far as I know, there isn't a slot on any phone for cash. How do you expect to get money to Steam? Phone companies aren't banks.
I think he means that he wants to add funds to his steam wallet from his phone credit, like you can do with some web based games. The answer to this is no. However you can buy steam gift cards from stores now and then redeem the gift card to your steam wallet.