express talk on macbook pro

Dear Support team,

I have installed NCH "Express Talk" on my Macbook pro, OS X 10.6.8.

SIP subscriber : Nexwaves Pte Ltd

I set up the line with full details, on Server name, SIP number, and password.

I also set up the "Network configuration"

Local SIP port to listen on: 5070

Local RTP ports to listen to starting from ... 8000

the rest of the boxes were unchecked.

I make call and receive call through express talk. That means the connection is successful with the above configuration.

- In the event I pick up call, I cannot receive the voice from the caller or transmit my voice to the caller through the Express Talk.

- In the event I call out, I cannot receive voice from the receiver nor transmit my voice to the receiver through the express talk.

- Both sides ring when calling each other.

The service provider confirms that the voice is blocked by the Mac OS setting or Firewall setting on Mac.

Please assist to trouble shoot and advise.

Arthur