Call Setup

Enable asynchronous message delivery: When enabled, Zello will record audio messages immediately after you press the PTT button and deliver messages asynchronously while minimizing delay.

When disabled, Zello establishes connection first and then streams the message. You won't hear the ready-to-send sound until the recipient's device responds.

For most users, we recommend keeping this setting enabled. Disable this setting if you wish to ensure that audio communication is strictly live.

Enable call pre-setup: Enabling this feature minimizes delay for repeat calls to the same contact by sending frequent keep-alive packets during one-on-one conversations. Disabling this setting may improve battery life at the expense of less predictable delays.

Networking (Mobile)

These features go into effect when your device is using a cellular connection.

Keep alive interval: This is the polling time between Zello and your cellular service provider. A longer time uses less data bandwidth and improves battery life. A shorter polling time keeps the user status display current and may improve connectivity.

For most users, we recommend using the default interval.

Use TCP only: Using TCP instead of UDP speeds up sign-in and improves connection reliability. It may also cause a slight delay for incoming messages.

Networking (WiFi)

These features go into effect when your device is using a WiFi connection.

Keep alive interval: This is the polling time between Zello and your internet service provider. A longer time uses less data bandwidth and improves battery life. A shorter polling time keeps the user status display current and may improve connectivity.

For most users, we recommend using the default interval.

Use TCP only: Using TCP instead of UDP speeds up sign-in and improves connection reliability. It may also cause a slight delay for incoming messages.

Security

Enable TLS: This enables transport layer security (TLS) encryption of all communication between the Zello client and server. The setting should be enabled for all users unless troubleshooting connection issues.