How can you unlock Samsung sch-b319?

Try this

1-Turn on the phone without sim card .

2-Pull off the battery cover and insert any non-accepted sim card (without turning off the handset)

3-Do full reset *2767*3855# , phone will reboot and goes to Menu .

4-Customize Sp-lock code *7465625*638*00000000*00000000#

5-Unlock your phone with new SP code #7465625*638*00000000#