said by pacpac:
I have the .cap file on Wireshark. What do I look for in order to confirm Asterisk do not proxy media?
Among other things, if it is proxying media, the vast majority of the packets will be RTP. With directrtpsetup properly working, you won't see any.
However, Wireshark does a great job of interpreting SIP and SDP, so just select one of those packets (if you are using other than port 5060, tell it to decode as SIP). You can then expand SIP, the header and/or body, and see where both endpoints have been told to send RTP.