Got it! So basically you want to unlock your phone to any network provider rather than just Austria A1.
Alright so there are two ways.
Installing another firmware for your phone or by entering a code that works. Im not sure about the code for S5 but its better if you download an official firmware for the phone and flash your device. This will work seamlessly and perfect enough to use on any network you desire.
For instance, download the stock firmware for s5 global and update/flash it on ur phone.
I must let you know that it can and will flag the samsung knox. Meaning that your warranty would be void but you will still get official updates and use the phone on any network u desire around the globe.
Plz press the thanks button if it helps
Sent from my SAMSUNG-SGH-I337 using XDA Premium 4 mobile app