[Sip] problem with NAT

[suresh t <sureshmaillist@yahoo.co.uk>]

hi all.. 

i got one doubt reg. NAT traversal of the SIP
messages...pls clarify me ASAP...

suppose if the user1 is using local Ip address and 
registers with the proxy with Ip address and port(the 
proxy registers the NATed IP and port(dynamic)). 
  
and suppose it is a chat like application, the user2 
wants to connect user1 through some private protocol, 
which is using TCP, but after a long time... 

in this case, the translation table(NAT) in the Router

of user1 is timed out and has been purged. then the 
user2 cannot access the user1's system. 

how can i solve the above problem..?

ur suggestion is highly appreciated.   

thanks in advance 
suresh 



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