[Freeswitch-users] Freeswitch is responding to contact's port when client behind NAT

Hi All, We`ve been using freeswitch since very long, It was good all over but it got stuck to a simple yet complex situation. We have Yealink T28P series phones behind NAT and freeswitch is unable to get them register. In the scenario freeswitch is at public IP. The reason we think is that freeswitch is using sip port in contact header to respond to. Is there anyway we can avoid this or force it to always send the response to destination IP instead of contact or via header ports because clients are behind NAT and response can only reach them if it respond to destination IP & PORT. Please revert if someone know how to solve this problem. It is very urgent. Regards