A NAS shares files and supports streaming, but it does so on your local area network. That is, in your house or apartment, and possibly for a short distance around if you are using Wifi.
To support "any location" you will need to use the internet, and I'm not aware of any simple way to have your NAS stream files over the internet to your phone. It would require your NAS to operate as a web server of sorts.
You might be able to achieve what you want using some form of cloud storage.
^ thas what i also had in mind of telling him
+2 to running off cloud storage.
if you want the smartphone streaming from NAS option, you need to shell out your apartment downpayment to do so. Its really expensive to maintain a wireless link with devices over a great distance/radius/coverage.