Lets say bitcoin become a global currency which replace fiat money.. If someone (physically )is asking for bitcoins and its urgent and i don't have phone to access the network and the one whos asking don't have the phone also.how can this transaction be done.because with fiat money you could just take the money out of your pocket and give him
Lets say bitcoin become a global currency which replace fiat money
Logically, if Bitcoin were to fully replace fiat money and be used for every transaction, then we should expect there would be some way of facilitating transactions easily, in pretty much every situation. Otherwise, people aren't going to adopt it if it is a worse solution that what is already available.
But to answer your question more directly: there are ways to transfer ownership of provably not-backed-up private keys, such as the OpenDime (disclaimer: I have never used an OpenDime, but understand how they are supposed to work, in concept). So if you had a device like the OpenDime that was loaded with the correct amount of BTC, you could just trade it to your counterparty. No internet connection needed.