Iphone 4 swap for samsung Galaxy S2 or S3 .

Iphone 4 with box and charger have headphones but due to hygiene i will not send them but if you really want them you can I use this on o2 so not really sure if its unlocked (i bought it off someone on o2 and they had no idea either but he thought it was i just have not tried it) Looking to swap for samsung galaxy s2 unlocked or o2 Phone is in great condition no marks at all