Will a bad esn iphone will work in other country?

Will a bad esn cellphone will work in another country.

By ESN you mean its a CDMA iPhone, one that works with Verizon or Sprint.

yes it will work but you will need to flash it to a new network. Some US budget carriers, and some foreign carriers allow you to activate these phones on their networks, by registering the MEID on their network. Major US carriers DO NOT REGISTER OTHER MEID's MAINLY PREPAID CARRIERS LET YOU DO THIS, BUT CHECK WITH THE CARRIER FIRST.

heres how to flash an iphone 4

an iPhone 4S is the easiest because it will have a Micro sim. It can be GSM unlocked Easily and you can pop in a sim from almost any GSM carrier.