I've taken another stab at this one way audio problem today.

I've run a wireshark capture, and looking at the RTP analysis it only has the down-stream, it doesn't record anything being sent upstream at all.

Below is the SIP graph, which shows RTP coming down, but none going up. But I don't know enough about SIP to know whether something is missing.

Any suggestions of what I should try now?

Would the dtmf's be sent in the sip packets, or in the rtp?

To preempt the easy answers and save some time:
- ports are open on EC2 config, 
- iptables turned off for the test,
- RTP port range uncommented in switch.conf.xml,
- softphone stun was set to stun.freeswitch.org

Cheers,
Fraser