Problem on RTP data access

[deep]

I face a problem while accessing RTP data from client machine.......
let imagine ur companies web server....ok..it's has two lan card ....
one for extranet i.e connected to the enternal world....and another to
the intranet.
now when a u want to access the google page i.e a http request ok...at
first it go to the
internal lan card port and then through proxy connection the request
goes through the external lan card port then to the google
server....clear
now problem comes on when i'm using rtp(real time transport protocol)
that times proxy doesn't able to map this protocol to the
intranet...bcoz generally rtp isn't enable to the proxy......
now my question is that is the proxy setting done by programming if yes
then how or if no then what would be the solution.......