when in bali last year i took my mobile its pre paid i go with voda phone in perth i bought a bx or bxc card in bali to put in the phone it didnt work so when i left for bali this year in april i bought an optus starter kit and bought a bxc one off theres it worked whats the easest way too go about it as when i come home i still want to go back to voda phone with my same no