Q:

Asterisk Server not accepting voice

I have installed AsteriskNow server with FreePBX on Virtualbox.
I am using a Softphone(3cxphone) to test the system. 
I could able to connect to Asterisk and make calls. But I can't here anything what other end is saying.
Also the call is got cut after 8-10 seconds.
I configured and tested my microphone and it is working properly.
Harikrishnan

A:

The problem is that the firewall is blocked the RTP (and RTCP) traffic. The session is established with SIP, hence you can do calls and receive calls but You dont listen, because the media traffic is blocked. 
Then, You should open the /etc/asterisk/rtp.conf file and edit the follow lines with the ports that You want use to RTP (and RTCP) protocol.
rtpstart=10000
rtpend=20000

RTP protocol works over UDP, then You should open this UDP port range. (In your Server and if You are using NAT You should configure the port forwarding too.

