Few days ago a friend asked me this questions. But i cannot understanding that how to i give him answer. At last i said him that, bitcoin is an online currency. Only this currency used in online marketplaces. It is not possible to use it in offline marketplace like offline currency.
But what is your best answer of this question?
You need some kind of connection to broadcast your transaction, so at the moment internet connection is required. However, there are works in progress to allow Bitcoin transactions to be broadcasted through Satellites.
Blockstream already has one in operation.