Hi , Sorry for previous email. Hit send too soon .

Good morning,

On my system i've a structure similar to:

  

 SIP Clients                    SIP Platform

[-------------------]        [---------------------------------]

                                              S1 @IP2 

     

  SIP UACs              SIP LB                    ...

 [NATted and            @IP1

 non Nattted]

                                               SN  @IPN

SIP LB is based on Kamailio dispatcher and is responsible of distributing the load between different Servers SIP UAS.

S1, S2,... SN Servers have a Kamailio Server too which will forward received balanced traffic to appropiate service (Presence , registrar,...)

Considering SIP LB and all SIP UAS have Public IP, how NAT from the UACs could be handled on this scenario?

Initially I thought NAT should be handled on SIP LB however I would like the most simple possible load balancer with no need to read user locations . Responsible of location users should be S1,S2,..:SN 

Then, would  it be possible to handle NAT of the SIP UACs from the SIP UAS  with NAT Helper module? What i'm afraid is:      If all traffic to S1,S2,..SN comes from SIP LB then nat_helper could think all clients are NATTed because top most via will be SIP LB.

What I need, I think, is that NAT Helper decides if there is NAT looking the Via Header added originally by UAC , and not the top most via (which would be SIP LB). Is that possible? If possible how should i configure Nat helper for that?

BR

Albert