sorry,I've no idea about that,because I don't have a cellphone~
This is the first step the card shows:From a Touch-Tone phone,dial 1-866 574-6250.
So,try this number,I think if the number can be used on cellphone,the card can work on cellphone too.
By the way,Last night I start a new card,it charged me 29c for about a 10minutes call.But several days ago,I'm sure it charged me 27c each time.So,now I'm not sure it cast 29c or 27c each time .