i have a treo 180 and want to unlock my phone but from what i have read u need to use certain codes and what i dont know is do thos coees stick to the sim card

because i want to activate the prepaid plan on my treo 180 but am not sure if it will work to start with and if i go to unlock it then and it doesnt work im sunk
so heres my question:
can i use my friends sim card to unlock my treo and then use a different card for service?

and as a side note if anyone knows if cingular will work with the treo 180 let me know plz