No media between 2 SBCs

Hello everybody,

I hope you're doing great

Right now I'm trying to assemble an scenario that involves two consecutive SDs, a registrar server and call generators, so it would go like this:

(10.10.10.80/10.10.10.96) (10.10.10.199)                          (172.18.2.95)    (172.18.2.99)               (192.168.1.98)                   (192.168.1.86 or 192.168.1.87)

sip client/s  ------------> SBC Server Access ----------> SBC Server Core  ---> 4250 Access -------------> 4250 Core --------------->     Asterisk or Sip Server

There is a local policy stating that registers are routed to the asterisk box and invites are routed to a sip server that plays an audio file when recieves an incoming invite (it doesn't challenge the registration).

The registers are working fine and I can see them cached in both boxes (yeah, double consecutive acces scenarios seem a little unusual but I get signaling working for registrations and calls), however, no media can be seen between the two sbcs, when you look at a trace, you can see that once the 200 OK has been recieved by the calling party (fom the called pary vía it's nearest sbc) both ends, start to send media but in none of the cases this traverses the closest SBC (I'm attaching a capture of the 4250 side of the scenario).