Quick answer: Both built-in voice and text are intentionally limited by distance and the environment. Communication tools can extend or alter those channels as part of play.
External chat changes the experience
The official FAQ strongly advises against separate voice software because it bypasses situations built around losing, muffling, or rerouting communication.
Keep walking
Play Big Walk Without a Microphone
Use Big Walk's official text chat for the whole game while preserving the same proximity, environment, and communication-tool limitations as voice.
Big Walk Walkie-Talkie: Verified BasicsLearn the officially described role of Big Walk walkie-talkies in proximity communication without relying on guessed spawn locations or puzzle routes.