Call quality issue with the app (iOS and Android)

[Rej]

We've received multiple complaints from our customers and have also experienced call quality issues ourselves when using the 3CX iOS and Android apps.

The issue isn't constant, but it occurs approximately 7 times out of 10. Internal calls work perfectly fine. However, during outbound calls through SIP trunks, we frequently receive complaints from the called party about noise on the line and difficulty hearing the caller clearly. Meanwhile, the caller can hear the called party loud and clear and the call quality indicator is green.

The issue occurs intermittently across multiple 3CX systems, all running the latest version and hosted on either Microsoft Azure or AWS. Most of these systems use the same SIP trunk provider but connect through different servers. However, we've also experienced the same issue with another SIP trunk provider (Twilio).

Interestingly, the issue only seems to affect calls made through the 3CX iOS and Android mobile apps. Calls made using desk phones, the Windows softphone, or the web client work perfectly fine.

I've already verified that the SIP trunk codecs are configured correctly and confirmed the settings with our VoIP trunk provider. We've also tried adjusting various settings, including "PBX Delivers Audio," enabling and disabling SRTP, and other user-level configurations, but nothing has resolved the issue.

Has anyone else experienced similar problems with the 3CX mobile apps? If so, were you able to identify the cause or find a solution?

 

[BrunoI_3CX]

Hello @Rej

As a first step, please ensure that both the 3CX Android and iOS applications are running their latest available versions, along with the latest OS updates for each device.

Additionally, please perform the following checks:

• Navigate to Admin > Dashboard > Troubleshooting > Firewall > Trigger the Firewall Check, and ensure that all tests pass successfully. Also, verify that the ports required for the remote 3CX Apps are correctly configured, as described in our 'Firewall & Router Configuration' document: For Android push notifications, ensure that port 443 (TCP outbound) is allowed. For iOS push notifications, ensure that ports 443, 2197, and 5223 (TCP outbound) are allowed.
• Navigate to Admin > Advanced > Network and ensure that 'Automatically bind to IPv6 adapters. Requires SIP service restart' is disabled. If enabled, disable it and restart the '3CX PhoneSystem 01 SIP Server' service under Admin > Dashboard > Troubleshooting > Services, ensuring that no active calls or actions are taking place.
• Confirm that the affected SIP trunks are configured using the default system templates.
• Test whether the behavior occurs on both Wi-Fi and mobile data to determine whether it is specific to a particular network connection.

If the issue persists after these checks, we recommend reproducing the behavior while collecting a packet capture from the affected system, with Verbose logging enabled, and reviewing the RTP streams for any jitter or abnormalities.

Alternatively, you may open a support ticket with us and provide the packet capture and Support Info bundle, along with the exact date and time, originating extension, and dialed destination of an affected call, for further investigation.