180 ringing not traversing the SBC and delay in 200 OK

Hello everyone

 

We're looking at an scenario where the sbc is recieving the 180 ringing on one side but we are not able to see it traversing the box and getting to the other side (no 180 ringing from the other side to the sbc to its destination).

 

In spite of that, the called party sends the 200 OK response but the SBC keeps resending (I think is the same message since the cseq value is the same in all messages) invites  (which kept being answered by the called party with 200 ok every time). Finally after about 3 seconds (too much time) the 200OK response traverses the SBC and gets to the originating party.