Voice Calls

Learn how to use encrypted voice call features in Mixin Messenger, supporting one-on-one and group calls with up to 1024 participants.

Voice Call Overview

Mixin Messenger provides high-quality end-to-end encrypted voice call services:

Feature	Description
One-on-One Calls	Fully encrypted private calls
Group Calls	Up to 1024 participants simultaneously
End-to-End Encryption	Call content completely encrypted
HD Audio Quality	Adaptive audio codecs
Low Latency	Optimized network protocols
Cross-Platform	Supports all mainstream devices

One-on-One Voice Calls

Initiate Call

Method 1: From Chat Interface

1. Open chat window with contact
2. Click phone icon in top right
3. Select "Voice Call"
4. Wait for other party to answer

Method 2: From Contact Info

1. Open contact details page
2. Click "Voice Call" button
3. Automatically initiates call
4. Wait for connection

Answer Call

When Incoming Call:

• Receive call notification
• Show caller information
• Slide to answer or reject
• Support quick reply messages

During Call:

• 🔇 Mute/unmute
• 📢 Speaker on/off
• ❌ Hang up call
• 📱 Switch audio device

Call Quality Optimization

Network Requirements:

• Minimum: 64 kbps
• Recommended: 128 kbps or higher
• Wi-Fi environment best
• 4G/5G network good

Audio Quality Settings:

1. Settings → Calls → Audio quality options
2. Select quality mode:
   • Data saver mode (64 kbps)
   • Standard mode (128 kbps)
   • HD mode (256 kbps)

Noise Reduction:

• Automatic noise reduction
• Echo cancellation
• Automatic gain control
• Background noise suppression

Group Voice Calls

Create Group Call

From Group Chat:

1. Open group chat
2. Click phone icon in top right
3. Select "Group Voice Call"
4. All members receive notification

From Group Info:

1. Go to group details
2. Click "Start Group Call"
3. Can choose to invite specific members
4. Start call

Join Group Call

When Invited:

• Call banner shows in group chat
• Click "Join" to participate
• Can leave and rejoin anytime
• Can join while call in progress

Actively Join:

1. Open ongoing group chat
2. View call prompt at top
3. Click join call
4. Automatically connects

Group Call Management

Host Functions:

• Mute all participants
• Remove participants
• Lock call (prohibit new joins)
• End call

Participant Permissions:

• Self mute/unmute
• Leave call
• Invite other members
• View participant list

Large Group Calls

Up to 1024 People:

• Supports massive scale calls
• Automatic load balancing
• Intelligent audio mixing
• Priority speaker audio

Performance Optimization:

1. Auto Adjust

   • Auto adjust quality based on network
   • Prioritize connection stability
   • Intelligent bandwidth allocation

2. Speaking Mode

   • Active speaker detection
   • Non-speakers auto lower volume
   • Reduce network bandwidth consumption

3. Group Transmission

   • Large calls auto grouped
   • Nearby users prioritized
   • Lower overall latency

Encryption & Privacy

End-to-End Encryption

Encryption Mechanism:

• Uses DTLS-SRTP protocol
• Independent key each call
• Perfect forward secrecy
• Cannot be intercepted by third parties

Encryption Process:

Initiator
  ↓
Generate temporary key pair
  ↓
Key exchange (encrypted)
  ↓
Establish encrypted channel
  ↓
Audio encrypted transmission
  ↓
Receiver decrypts
  ↓
Play audio

Privacy Protection

Call Privacy:

• Server does not record call content
• Does not save call recordings
• Only records call duration metadata
• End-to-end encryption protection

Metadata Protection:

• Minimize metadata collection
• Encrypted transmission path
• Hide IP address (optional)
• Regularly clean logs

Verify Call Security

Security Code Verification:

1. View security code during call
2. Compare numbers with other party
3. Matching numbers indicate security
4. Mismatch may indicate attack

Best Practices:

• Verify before important calls
• Regularly check security code
• Terminate immediately if abnormal
• Confirm through other means

Call Features

Audio Device Switching

Supported Audio Outputs:

• 📱 Phone earpiece
• 📢 Speaker
• 🎧 Wired headphones
• 🎧 Bluetooth headphones
• 🎧 Bluetooth speakers

Auto Switch:

• Auto switch when plugging headphones
• Resume speaker when unplugging
• Auto detect Bluetooth connection
• Intelligent multi-device management

Call Recording

Considerations:

• Mixin does not provide built-in recording
• Protects call privacy
• Using system recording needs to inform other party
• Comply with local laws

Call Transfer

Transfer Call:

1. Click "Add Participant" during call
2. Select contact to transfer to
3. Establish three-way call
4. Can choose to leave

Advanced Features

Call Settings

General Settings:

1. Default Audio

   • Set default speaker/earpiece
   • Auto switch Bluetooth
   • Ringtone volume adjustment

2. Incoming Call Settings

   • Choose ringtone
   • Vibration on/off
   • Do Not Disturb integration

3. Network Optimization

   • Wi-Fi preferred
   • Cellular data limits
   • Low bandwidth mode

Call History

View Records:

1. Settings → Calls → Call Records
2. View all call history
3. Shows duration and time
4. Quick redial function

Record Management:

• Clear call records
• Export call history
• Hide specific contacts
• Auto clean old records

Call Notifications

Notification Settings:

1. Incoming Call Notification

   • Full-screen incoming display
   • Banner notification
   • Lock screen display
   • Custom ringtone

2. Group Call Notification

   • Notify when call starts
   • Member join reminder
   • Mute notification option

Troubleshooting

Common Issues

Cannot Hear Other Party:

1. Check volume settings
2. Confirm not muted
3. Switch audio output device
4. Restart call

Poor Audio Quality:

1. Check network connection
2. Switch to Wi-Fi
3. Lower quality settings to save bandwidth
4. Close other apps

Connection Failed:

1. Check network permissions
2. Confirm firewall settings
3. Try switching networks
4. Update app version

Echo or Noise:

1. Lower volume
2. Use headphones
3. Turn off speaker
4. Check microphone permissions

Network Issues

Weak Network Optimization:

1. Auto Downgrade

   • Auto lower audio quality
   • Maintain connection stability
   • Auto upgrade when network recovers

2. Reconnect

   • Auto reconnect mechanism
   • Maintain call state
   • No manual operation needed

3. Data Saver Mode

   • Greatly reduce data usage
   • Suitable for limited data scenarios
   • Moderate quality compromise

Permission Settings

Required Permissions:

• 📱 Microphone access
• 📞 Phone permission (caller ID)
• 🔔 Notification permission
• 🌐 Network access

Check Permissions:

1. System Settings → Apps
2. Find Mixin Messenger
3. Check permission status
4. Enable all

Comparison with Other Apps

Feature	Mixin	WhatsApp	Telegram	Discord
End-to-End Encryption	✅ All	✅ One-on-one	❌	❌
Group Call Size	1024 people	32 people	Unlimited (broadcast)	25 people (video)
Audio Quality	HD	Standard	HD	HD
Call Encryption	✅	Partial	❌	❌
Free	✅	✅	✅	✅
Cross-Platform	✅	✅	✅	✅

Best Practices

Call Etiquette

1. Before Initiating Call

   • Message first to ask if convenient
   • Avoid late night disturbances
   • Confirm other party online

2. During Call

   • Keep background quiet
   • Express clearly
   • Control time

3. Group Calls

   • Mute when not speaking
   • Speak in order to avoid confusion
   • Use text to assist communication

Security Recommendations

1. Sensitive Calls

   • Verify other party identity
   • Check security code
   • Pay attention to surroundings

2. Public Places

   • Use headphones
   • Lower volume
   • Protect privacy

3. Important Meetings

   • Test audio quality in advance
   • Prepare backup plan
   • Use stable network

Common Questions

Are calls completely encrypted?

Yes:

• End-to-end encryption
• Server cannot eavesdrop
• Uses military-grade encryption
• Regular security audits

How much data do calls consume?

Depends on quality settings:

• Data saver mode: ~0.5 MB/minute
• Standard mode: ~1 MB/minute
• HD mode: ~2 MB/minute
• Group calls same

Can I record calls?

• Mixin does not provide recording
• Protects call privacy
• Third-party recording needs to inform other party
• Comply with laws

Group call size limit?

• Maximum 1024 people
• No duration limit
• Free to use
• Auto optimize performance

How long are call records saved?

• Only save metadata
• Do not save call content
• Records saved 30 days
• Can manually clear

International call quality?

Excellent:

• Global server coverage
• Intelligent routing optimization
• Auto select optimal nodes
• Low latency guarantee

Can I call on multiple devices simultaneously?

No:

• Only one device at a time
• Auto log out other devices
• Ensure call quality
• Prevent echo interference

Technical Details

Audio Codecs

Supported Formats:

• Opus (primary)
• AAC
• G.711
• AMR

Adaptive Encoding:

• Auto switch based on network
• 8-510 kbps dynamic adjustment
• Ultra-low latency optimization
• Packet loss resistance algorithm

Network Protocols

Transport Protocols:

• WebRTC technology stack
• DTLS-SRTP encryption
• ICE/STUN/TURN
• UDP preferred, TCP backup

Connection Establishment:

1. Signaling exchange
2. NAT traversal
3. Key negotiation
4. Media transmission
5. Keepalive maintenance

Server Architecture

Distributed Deployment:

• Global multi-region nodes
• Intelligent load balancing
• Disaster recovery backup
• 99.9% availability

Privacy Protection:

• Relay servers do not decrypt
• Minimal metadata recording
• Regular data cleaning
• Open-source auditable

Related Resources

• Encrypted Chat - Learn about end-to-end encryption
• Group Features - Group management details
• Privacy Protection - Privacy security guide
• Common Questions - Quick start guide