Troubleshooting

Troubleshoot Audio Issues in SipLine

No sound, one-way audio, or choppy calls? This guide helps you systematically diagnose and fix the most common audio problems in SipLine.

10 min read

Prerequisites

SipLine installed and registered with a SIP account (status shows Registered)
An audio device connected to your computer (headset, speakers, or built-in audio)

1Check Windows Audio Settings
2Verify SipLine Audio Configuration
3Run SipLine's Built-in Audio Test
4Check Firewall Rules for RTP Traffic
5Verify Codec Negotiation
6Check NAT and Network Configuration

Check Windows Audio Settings

Open Windows Settings > System > Sound and verify your default playback and recording devices are set correctly. Speak into your microphone and confirm the input level meter moves. Play a sound to confirm your speakers or headset are working.

Right-click the speaker icon in the system tray and select Sound settings for quick access. Make sure the correct device is set as default, not just enabled.

Verify SipLine Audio Configuration

In SipLine, go to Settings > Audio. Check that the correct playback device, recording device, and ringtone device are selected. If they are set to Default, SipLine will use whatever Windows has configured. Explicitly selecting your devices avoids issues when multiple audio devices are connected.

If you recently plugged in a USB headset or Bluetooth device, restart SipLine to refresh the device list.

Run SipLine's Built-in Audio Test

SipLine includes an audio test feature under Settings > Audio > Test. Click the test button to play a tone through the selected playback device, then record a short clip through the microphone. If you hear the tone and your recording plays back clearly, your local audio chain is working correctly.

If the audio test works but calls still have no sound, the problem is likely network-related (firewall, NAT, or codec), not your audio devices.

Check Firewall Rules for RTP Traffic

SIP uses UDP port 5060 for signaling, but the actual audio is carried over RTP, which uses a range of UDP ports (typically 10000–20000). Open Windows Defender Firewall > Advanced Settings and make sure SipLine is allowed through the firewall for both inbound and outbound UDP traffic.

Corporate firewalls and VPNs often block UDP traffic on non-standard ports. If you are on a company network, contact your IT department to allow RTP traffic.

Verify Codec Negotiation

Mismatched codecs between SipLine and your provider can cause silent calls. In SipLine, go to Settings > SIP Accounts > [Your Account] > Codecs and check which codecs are enabled. Make sure at least one codec matches what your provider supports — G.711a (PCMA) is the safest choice for compatibility.

Enable SipLine's SIP log under Settings > Advanced > SIP Logging to see the SDP negotiation. Look for the m=audio line to confirm codecs were agreed upon.

Check NAT and Network Configuration

If you are behind a NAT router (most home and office networks), RTP packets may not reach your computer. In SipLine, go to Settings > SIP Accounts > [Your Account] > Network and enable STUN. Use a public STUN server like stun.l.google.com:19302 to help SipLine discover your public IP address.

Use SipLine's built-in Network Diagnostics tool (in the Network settings page) to quickly identify connectivity issues. If STUN does not resolve the problem, try enabling ICE (Interactive Connectivity Establishment) for more robust NAT traversal.

Frequently Asked Questions

I have one-way audio — I can hear them but they cannot hear me (or vice versa). What causes this?

One-way audio is almost always a NAT or firewall issue. Your SIP signaling gets through, but RTP packets (the actual audio) are blocked in one direction. Enable STUN in SipLine's network settings, and make sure your firewall allows both inbound and outbound UDP traffic on the RTP port range (10000–20000).

I hear an echo during calls. How do I fix it?

Echo is typically caused by audio leaking from speakers back into the microphone. Use a headset instead of speakers to eliminate this. If you must use speakers, lower the speaker volume and enable any echo cancellation features in SipLine under Settings > Audio > Echo Cancellation.

Audio is choppy or robotic during calls. What should I do?

Choppy audio indicates packet loss or jitter on your network. Try the following: (1) use a wired Ethernet connection instead of Wi-Fi, (2) close bandwidth-heavy applications (streaming, downloads), (3) enable QoS on your router to prioritize VoIP traffic, (4) in SipLine, try increasing the jitter buffer size under Settings > Audio > Jitter Buffer.

I have absolutely no audio in either direction. Where do I start?

Start with the basics: (1) make sure your audio devices work in other applications, (2) verify SipLine is using the correct devices under Settings > Audio, (3) run the built-in audio test, (4) check your firewall allows SipLine through for UDP traffic, (5) enable STUN in the account's network settings. If the audio test works but calls are silent, the issue is network-related.

Audio works with my headset but not with my speakers. Why?

SipLine may be configured to use a specific audio device rather than the Windows default. Go to Settings > Audio and change the playback device to your speakers, or set it to Default and then change the Windows default output device. Also check that the speaker volume is not muted in the Windows volume mixer.

Does SipLine support noise suppression?

SipLine includes built-in noise suppression that can filter out background noise during calls. Enable it under Settings > Audio > Noise Suppression. For best results, combine this with a quality headset that has its own hardware noise cancellation.