apple iphone 5 black 16gb 1 month old ?

only had the phone a month, its in perfect condition as its been in a bumper case and has had a screen protector on since it was opened. the phone comes in its original box with all cables and original ear pod earphones, im only selling the phone due to christmas only being round the corner so serious buyers only please. the phone was bought on o2 but im not sure if its unlocked to all networks!