VOIP problem with ININ and Polycom

Hello,

We had implement VOIP phone using hosted solution (vendor ININ).  The connection establish successfully but when user attempted to make the phone call, there is no audio pass through.  For testing purpose, we had configured the firewall to allow the phone to goes to Any destination and Any Port with no UTM profiles setup.

We are running on firmware version 5.2.4.

Base on the support engineer troubleshoot session, the phone is using https to establish the session and then switch over to RTP protocol for calling.  This caused the firewall to not able to recognize the SIP traffic since the SIP traffic is pass through using TLS encryption.

Test scenario - I put the phone on the DSL line and have it connected to and everything work fine.  But behind the fortigate, no voice coming through.

Anyone know a work around to get the voice audio to work behind the firewall?

Thanks,