Hello Joshua,
Not sure about RTP trace packets, but Traceroute will provide you the call path.
"Traceroute support—Allows the user to use traceroute to see the path that a Cisco SIP IP phone traverses in the route to its desired destination."
To troubleshoot a call, you can also use dialed number analyzer.
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/dna/7_0_1/bw-dna/dnai.html
Debugs on GW will also verify if the call is hitting the gateway or not and provide diagnostics.
debug isdn q931
Depends on what you are troubleshooting.
Hope this helps...