Voice and text through your B9X Voice Server

Features at a glance

• Four clear tabs: Talk, Server, Audio, and Messages.
• Manual hold-to-talk and optional hands-free VOX.
• Live microphone and speaker analog meters.
• Saved microphone gain and speaker level controls.
• Adjustable VOX trigger, VOX time-off delay, and playback cushion.
• Server password and encryption-key fields with independent Show/Hide controls.
• Optional device-protected storage for remembered credentials.
• Always Stay Connected for startup connection and automatic retries.
• Saved screen name and persistent text-message history.
• Optional Android text-to-speech playback of new received messages.

This is a half-duplex client: users take turns speaking through a compatible B9X Voice Server. It is not a standalone server, a full-duplex telephone client, or a Windows radio-interface replacement. It does not include COM-port RTS/DTR control, a Morse IDer, DTMF server switching, or OpenAI voice commands.

What you need

• An Android phone or tablet running Android 8.0 or later.
• A working microphone and listening output. Headphones are recommended, especially for VOX.
• A Wi-Fi or mobile-data connection that can reach your B9X Voice Server.
• The server’s hostname or IPv4 address, UDP port, password, and matching 32-character encryption key.
• For named text chat, another compatible client with support for the app’s TMSG messaging format.
• For spoken messages, an available English voice in the phone’s Android text-to-speech system.

The normal voice format is 11025 Hz, stereo, 16-bit PCM. The server port normally used is UDP 18000; your server operator may use a different port. The app supports a mono option for installations that specifically require it.

Install and open the app

1. Download the Android APK supplied for this application.
2. Open the downloaded APK on the Android device. If Android asks, allow installation from the browser or file manager you are using, then approve installation.
3. Open B9X PTT Chat. That is the launcher label used by this version.
4. When connecting for the first time, allow microphone permission. On newer Android versions, allow notifications so the ongoing voice-session notification is visible.

A source-project ZIP is not an installable APK. If you received the B4A project rather than an APK, it must first be built into an Android application. The following instructions describe using the installed app.

The four tabs

Set up your server connection

1. Open Server.
2. Enter the actual hostname or IPv4 address of your B9X Voice Server. Do not include https://, a web-page path, or a port in the address field.
3. Enter the server’s UDP port.
4. Enter its password and the exact 32-character encryption key. Both must match the server. The key must use printable ASCII characters.
5. Leave Local UDP Port at 0 so the phone chooses an available local port. Use a fixed local port only if your particular installation requires it.
6. Leave Stereo PCM checked for the normal configuration. Only change the format while disconnected and only to match the server.
7. If desired, select Remember password and key on this device.
8. Tap Save Settings, return to Talk, and tap Connect.
9. Wait for the status to show Connected before transmitting.

Initial defaults

These are sample defaults, not credentials for every B9X server. In particular, 192.168.1.1 must be changed unless that is the actual server address. Saved custom settings take precedence. Use the values supplied by your server operator.

The password and key start hidden. Each has its own SHOW / HIDE control. Revealing one does not reveal the other; visibility returns to hidden when the screen is recreated. Connection fields are locked while a connection attempt, active session, or automatic-retry session is running. Disconnect before changing them.

Talk and listen

1. Connect to the server and keep VOX disabled for the first test.
2. On Talk, press and hold HOLD TO TALK.
3. Speak normally while the app shows TRANSMITTING.
4. Release the control to stop sending and listen.
5. When another user speaks, the app shows RECEIVING and the speaker meter responds.

Manual transmission and VOX are inhibited while incoming voice is being received. Changing tabs, leaving the screen, or canceling a touch releases manual hold-to-talk. The microphone meter can move without transmitting; it shows the measured input, not proof that audio is being sent.

Start with two working clients on a LAN and verify audio in both directions. Then test the public server hostname over mobile data. A remote client normally does not need its own incoming port-forwarding rule; the server’s public UDP path must work.

Analog meters and audio levels

The microphone and speaker needles follow measured voice audio. They are not just connection indicators. The microphone indication follows microphone gain; the speaker indication follows the app’s received-voice level control. They operate during an active connection attempt or session. An idle, disconnected app does not keep the microphone open.

dBFS means decibels below digital full scale. Normal voice appears below 0 dBFS. The high-level indicator identifies very high measured levels; too much gain can distort the sound. These meters are not RF signal-strength or transmitter-power meters.

The phone’s media-volume buttons also affect listening volume. The app saves audio settings when changed and when you leave it. Hardware volume, headphones, and the selected Android audio route can still affect what you hear.

Hands-free VOX operation

VOX automatically sends microphone audio when its level exceeds the trigger. Open Audio and select Enable VOX (hands-free transmit). Set the trigger and delay, then return to Talk to use it.

If VOX stays on in a quiet room, increase the trigger or reduce microphone gain. If normal speech does not trigger it, decrease the trigger and check microphone permission and gain. A one-second delay equals 1000 milliseconds.

VOX transmission pauses on Server, Audio, and Messages so editing settings or composing messages does not accidentally transmit your speech. Return to Talk for voice operation. Incoming voice and spoken-message playback also inhibit VOX.

Playback buffering for Wi-Fi and mobile data

The Playback cushion control is on Audio. It offers 100–400 ms, with an initial value of 150 ms.

Start at 150 ms. If received audio arrives unevenly on mobile data, try 200 ms, then 250 ms. Larger settings add listening delay. Connection quality also depends on signal strength, congestion, and the server’s connection.

Buffering helps smooth uneven packet arrival; it cannot recreate speech that never reaches the phone or fix a sustained outage. Test with the same server and another known working client before changing several settings at once.

Text messaging and screen names

1. Open Messages.
2. Enter your screen name and tap Save. The initial name is Guest; choose something other users will recognize.
3. Connect to the B9X Voice Server if you are not already connected.
4. Enter a short message and tap Send Message.
5. Review the message history below. Entries show the sender and date/time; your sent entries also show You.

The screen name is also saved when sending or leaving the app. History remains on the phone after restarting and can be scrolled to older entries. Clearing app data or uninstalling the app removes that local history.

Who receives a message?

Messages are broadcast to everyone connected to the same server, subject to the server allowing broadcasts for the credentials in use. They are not private, one-recipient messages. A screen name is a display label, not an authenticated identity.

The chat uses a TMSG identifier to distinguish text chat from other broadcast types. Other clients need compatible TMSG support to show sender names and text correctly. An older client may show an encoded broadcast rather than a readable chat entry. Simply supporting B9X voice audio does not guarantee compatible named text chat.

Message length

Keep messages short. Screen names allow up to 32 UTF-8 bytes—up to 32 ordinary English characters, or fewer for some other characters. Message capacity depends on the name and text used, typically around 100–140 English characters. Unicode and punctuation are supported within that limit. Oversized messages are rejected with an explanation rather than silently shortened.

A queued notice means the app accepted the message for sending. It is not a delivery or read receipt, and it does not prove every other user received the message. Repeated server echoes with the same message ID are not displayed as separate messages.

Hear received messages spoken aloud

On Messages, select Enable text to speech. The app reads newly received messages in the form “screen name says: message.” This option is saved for future sessions.

Speech uses the phone’s Android text-to-speech engine; it does not need an OpenAI API key. If the status asks for an English voice, install one in the device’s text-to-speech settings. The chosen Android engine and voice determine whether a download or network connection is needed.

• Only new received messages are read. Your outgoing messages, their echoes, stored history, and unrelated broadcast types are not read aloud.
• Speech waits while voice is being sent or received.
• If incoming voice starts during a spoken message, speech stops and retries that message after voice traffic is quiet.
• VOX is inhibited during speech and briefly afterward to prevent the spoken message from being transmitted back through the microphone.
• Manual PTT interrupts queued speech. Disconnecting or closing the app stops speech.
• History and normal text messaging still work if speech is disabled or unavailable.

Spoken-message volume follows the app’s Speaker level from mute through 100%, together with Android media volume. Settings above 100% do not further amplify Android speech. The speaker needle measures received voice audio; it is not a separate speech-engine meter.

Always Stay Connected and background operation

Select Always Stay Connected on Server to connect when the app opens. After a connection timeout or a detected loss, the app waits about one minute and attempts a fresh connection. Enable remembered credentials if you want startup connection to work after Android has restarted the app’s process.

Android battery restrictions and other apps taking audio focus can affect background behavior. A notification indicates an ongoing session/service, not a guarantee that every server connection is currently established. Check Talk for the actual connection state.

Saved settings and credentials

Server fields save with Save Settings, Connect, or when you leave the app screen. Audio controls save when adjusted. The screen name, text-to-speech preference, and message history are also retained.

If Remember password and key on this device is selected, the credentials are encrypted using a device-bound Android Keystore key. Uncheck Remember to remove the saved credential entry. Revealing a field with Show does not change the server’s credentials.

Clearing app data or reinstalling may require entering credentials again. Device-bound protected credentials are not intended to be copied to another phone. Data protection on the phone does not change the network security capabilities of the existing B9X Voice Server.

The app does not provide OpenAI transcription or OpenAI speech generation. Spoken text messages use the selected Android speech engine. Remember that broadcast messages are shared with the server’s connected group.

Troubleshooting

For support, note your Android version, device model, app version, server port, Wi-Fi/mobile-data connection, and the relevant settings or status message. Do not send your server password or encryption key.