I'm having some strange issues with making calls using Zoiper. This is on a Lenovo Yogo Tablet 2-830F. Android version 5.0.1 Zoiper version 1.29 for Android, using the Open SLES audio driver and IAX protocol. The network connection is through WiFi.
When making an outbound call from the tablet, to any extension, internal or external number, the recipient does not hear my voice. RX audio from the recipient is received and heard fine. If someone calls the tablet extension, then audio works both ways without issues.
I have tried using the Java driver, or changing the listening port to not be 'random', but that does not solve the issue.
Can anyone offer me additional advice to track down the cause of this and possibly get it fixed?