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Shweta GargShweta Garg 

System.CalloutException: Unable to tunnel through proxy. Proxy returns "HTTP/1.0

Hello Developers,

While calling webservice from Salesforce Org,I am getting an Exception "System.CalloutException: Unable to tunnel through proxy. Proxy returns "HTTP/1.0 ".I have made a lot of search and found that This is a Firewall issue.
I have added these IP ranges in my Salesforce Org. East Coast Data Center (set one) East Coast Data Center (set two)  MidWest Data Centers  MidWest Data Centers West Coast Data Center (set one) West Coast Data Center (set two)  Japan Data Center

here .-> -
I have added the IP address Like this. But Still I am getting the same issue. I suspect  these ip address should be added at the server side(where web service resides)?Am I right. Or i am doing mistake while adding IP address.
Please suggest me with your ideas.