For Bypassing proxy servers you need to add the following property
bypassProxyOnLocal="true"
in BasicHttpBinding tag from web.config file of your wcf application.
Sample code,
<binding name="higherMessageSize_BASIC" closetimeout="00:30:00" opentimeout="00:30:00" receivetimeout="00:30:00" sendtimeout="00:30:00" bypassproxyonlocal="true" hostnamecomparisonmode="StrongWildcard" maxbufferpoolsize="524288000" maxreceivedmessagesize="65536000" messageencoding="Text" textencoding="utf-8" usedefaultwebproxy="true" allowcookies="false"></binding>
Thanks & Regards,
BlueSathish