Soon we will implement in-app exchange service, which you may use in order to top up your wallet, using other cryptocurrency coins that you have. For example, if you want to top up your BTS wallet using your altcoins, you need to launch your BTS application, go to Exchange option, choose to top up using the altcoin, you may choose it either by the ticker or the title. Then you will see the address where you need to send your altcoins in order to receive BTS coins in your wallet. Pay attention to the minimum amount for exchange. Then you go to your altcoin wallet or stock exchange and make a transaction using this address, after some time you will receive BTS coins to your BTS wallet.