| Description |
This article describes how to troubleshoot issues on Viber voice and video calls.
On mobile devices, when connected to the firewall, even allowing Viber on the application control and on the web filter the call is getting unstable and unable to establish. |
| Scope | FortiGate. |
| Solution |
This is because the Viber application signature on the application control is only intecepting default TCP ports which can only allow/block Viber messaging. TCP/80
Reference: https://www.fortiguard.com/appcontrol/26178
However, since Viber uses RTP for VOIP traffic it is most common to use UDP for faster data transmission. Having a Viber application signature is not enough to allow voice calls and video calls on mobile devices.
As a workaround, enable Unknown Applications on the Application Control.
It is also possible to craft a custom application signature for Viber that intercepts UDP ports. |
