One-way audio or not audio at all

• /etc/init.d/iptables stop

Device is SIP

• rtp debug, watch to see whether or not audio is coming/leaving
• Make sure sip.conf is correctly configured if Asterisk is behind NAT
• Make sure NAT settings are correct (nat=yes) (in provider/device settings)
• Make sure you are using the same RTP range as your provider
• Make canreinvite = no in device settings
• Remove T.38 Support from device settings

• In /etc/asterisk/sip.conf find lines:

t38pt_udptl = yes
t38pt_rtp=no
t38pt_tcp=no

and change to:

;t38pt_udptl = yes
;t38pt_rtp=no
;t38pt_tcp=no

Reload Asterisk.

Device is H323

• While connecting with H.323 client you get no audio or garbled audio and messages like this on Asterisk console: rtp.c:489 ast_rtp_read: Unknown RTP codec 107 received. Try to disable Speex or some other codec on Asterisk or/and client side.
• When no audio in H323 calls, make sure in /etc/asterisk/h323.conf you have binaddr set to your servers real IP address.
  • 
  • Restart Asterisk after that

See also

• One way audio problems