Cell phone used in breaking bad specially Walt's second phone?

Not a clue, but out of curiosity--why?

May be to buy one or sth similar :) The power of heisenberg :D I know its crazy

Not so crazy...I want to say it's a Nokia and you should bring the pic to a cell phone carrier but thats kinda not much help. I'm still trying to find an exact replica of the green army jacket he wears in Felina and at the start of 501 but can't match it exactly. I found one online that was close except for the collar then I found another but it had buttons on the front pockets. Once I find that a cheap pair of reading glasses and jeans will complete the ensemble! Good Luck!

Only based on the picture you've posted, I thing the one you're looking for is the samsung sgh-a437.

For my part, i'm looking for the one from the last season and it's probably the zte z221. If someone can confirm.