cisco 1811 configured with nat overload and route-map not showing any rtcp packets

jrs91

I'm setting up VQManager to monitor my voip network and keep qos statistics on all of our calls.

I've configured port mirroring on 2 interfaces (an exteral asterisk server and the firewall) so that I can capture all sip and RTP data travelling between various endpoints.

For some reason, even though the udp/rtp is coming through without problems, and using wireshark I can see RTCP sender reports going back and forth between most endpoints, I don't see a single RTCP Sender report coming from my voip trunk provider.

Here is the relevant configuration from my router:

interface FastEthernet0
bandwidth 10000
ip address 20x.x.x.x 255.255.255.240
ip nat outside
ip virtual-reassembly
speed 10
full-duplex

ip nat inside source list 10 interface FastEthernet0 overload
ip nat inside source static 10.101.0.4 20x.x.x.x route-map MAP
!
access-list 10 permit 10.101.0.0 0.0.0.255
access-list 101 permit udp host 10.101.0.4 range 10000 65500 any
access-list 101 permit udp host 10.101.0.4 eq 5060 any

Does anyone have any ideas why i'd be seeing the rtp traffic but no rtcp?