One way audio with OpenVPN

Hi All;

I am having problems with audio when connecting a zoiper phone through an OpenVPN server to an AsteriskNOW.
The VPN is established successfully, and the phone’s sip account is registered as well. But there is one way audio with the other.
Example:
When I call the SIP phone connected through VPN, the other person on the SIP phone connected through OpenVPN can hear me, but I can not hear him.
I’m running AsteriskNOW 13
FreePBX 12.0.74

Any suggestions.

Thanks

Convert your Zoiper SIP extension to AIX2 and set your “external” extensions up as AIX extensions instead of SIP.