number not so sure but as far as the phone u would have to call boost and talk to them about it because I have an old nextel phone that I wanted to put on my boost account and according to the website they said i could use it and then when I emailed them big mistake....they said it would not work. and yes when u run out of minutes u just buy more. but i hope u have done ur research on boost because its like 20 cents per minute unless u talk to people who r on boost. and if u use it for the walkie its $1/day for unlimited. not bad but if u dont use the walkie that much it could be.......also u might look into if they have the unlimited in ur area. which is better than just keep buying top-up cards every few days.