[SR-Users] Forward register to multiple Asterisk

Hello, I am trying to forward the register to multiple Asterisk using Kamailio. The basic Idea is: Softphone A---->Kamailio-----> Asterisk 1 ------> Asterisk 2. I follow Asipto howto http://lylix.net/kamailio, but the problem I see in my case, is that registration IP in Asterisk is Kamailio´s IP. This causes calls going from kamailio to asterisk and then back to kamailio. In my scenario, I need that softphone A IP appeard in Asterisk realtime contact IP. The call path would be: Softphone B -> kamailio -> Asterisk 1 or Asterisk 2 (depending on dispatcher) -> Softphone A Following Asipto how to the call goes Softphone A -> kamailio -> asterisk -> kamailio Softphone B Hope I explain myself clearly. Thank you in advance.