When Sony Walkman was ruling the mobile music world the only accessory was the ear phone. When the old ear phone is worn out you buy a new ear phone. That is the only accessory. After the emergence of new generation music players the accessories started pouring in. These accessories are not always manufactured by the music player manufacturers. Some times they are manufactured by others to suit the popular music players.
Nokia accessories are manufactured by Nokia but models produced by other also fit these phones. The Ipod Touch charger also could be replaced by the models manufactured by other companies which have the same specification but iphone head set is very difficult to be replaced by another one as the iphone head set is consisting of a microphone for the telephone and the controls are built in
However the models manufactured by many other companies give the same performance as the original ones.