SharePoint Internet Zone access from the WCF service provides "Unable to connect to the remote server" error

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.NET

WCF

SharePoint2010

, +

Hello,

I have SharePoint server and configured the Internet Zone url mapping in AAM and make SharePoint Site live.
And also set the firewall settings for SharePoint Site ID and Port (For example : 15.24.145.256:555)

Now I m able to access the SharePoint Site by out side.

I have create one WCF service. WCF service is also live on one IP:Port.

But When I tried to access the SharePoint Site though its Internet zone url from the WCF service(using SharePoint client object Model), its Providing "Unable to connect to the remote server" Error.

Stack trace :
at System.Net.HttpWebRequest.GetRequestStream(TransportContext& context)
at System.Net.HttpWebRequest.GetRequestStream()
at Microsoft.SharePoint.Client.SPWebRequestExecutor.GetRequestStream()
at Microsoft.SharePoint.Client.ClientContext.GetFormDigestInfoPrivate()
at Microsoft.SharePoint.Client.ClientContext.EnsureFormDigest()
at Microsoft.SharePoint.Client.ClientContext.ExecuteQuery()
at Cygnet.SharePoint.SPServices.Service.CreateConnection(String serverUrl, String userName, String password, String domainName, String authenticationMode) in c:\inetpub\wwwroot\m1Share\SPServices\Service.svc.cs:line 75

Can you plz give me some direction to how to solve this issue?