Here's why:
* No Apps in SoulSilver: Pokemon SoulSilver is a Game Boy Advance game. It doesn't have the concept of "apps" like modern smartphones do.
* The Pokeflute: The Pokeflute is a physical item in the game that you can use to call back Pokemon. You get it in the game by completing a specific quest. It doesn't work through an app.
How to Get the Pokeflute in Pokemon SoulSilver:
1. Beat the Elite Four: You need to become the Champion of the game.
2. Talk to the Old Man: After defeating the Elite Four, go back to the house in Goldenrod City where you first got your starter Pokemon. There will be an Old Man inside who gives you the Pokeflute.
Let me know if you have any other Pokemon SoulSilver questions!