SD in proxy mode with NAT when both part are located in the acccess side of SD

Hi

 

I use SD4250 CX6.2.

SD has 2 physical interfaces, one in access side, one in core side.

 

case 1

until now I'm used to use SIP trunking going from trusted access side towads core side (and reverse).

ipbx <>  [private access side of SD  | core side of SD] <> softswitch

no problem with this architecture.

 

case2

I also use this SBC for softphone from internet access towards a registrar of our sofstswitch on our core side. SD behave in a stateful proxy mode with NAT and topology hiding

internet <>  [ public access side of SD  | core side of SD] <> softswitch registrar

no problem with this architecture.