I am using Cisco 1841 and running VoIP based telephone system ( Not Cisco). I have a one way audio problem. If I call out within the network to outside world, I can hear them but they can't hear me. Seems like RTP is having some probelms.
If I replace Cisco 1841 with Netgear router then it works fine without any problem, I think I have mis configured Cisco 1841( NAT or firewall rule) which casuing the RTP porblems.
I have attached the config if you can spot any problem then please advise. I may have not right ACL entries or firewall rules to allow outbound communication.