We've got to access a web service that uses soap11... no problem I'll just set the binding as: BasicHttpBinding wsBinding = new BasicHttpBinding(BasicHttpSecurityMode.TransportWithMessageCredential); Nope. No dice. So I asked the host of the service why we're having authentication issues and he said that our config needed to have this custom binding: <bindings> <customBinding> <binding name="lbinding"> <security authenticationMode="UserNameOverTransport" messageSecurityVersion="WSSecurity11WSTrustFebruary2005WSSecureConversationFebruary2005WSSecurityPolicy11" securityHeaderLayout="Strict" includeTimestamp="false" requireDerivedKeys="true" keyEntropyMode="ServerEntropy"> </security> <textMessageEncoding messageVersion="Soap11" /> <httpsTransport authenticationScheme ="Negotiate" requireClientCertificate ="false" realm =""/> </binding> </customBinding> </bindings> Only problem is we're creating our binding programmatically not via the config. So if someone could point me in the right direction in regards to changing my BasicHttpBinding into a custombinding that conforms to the .config value provided I'll give them a big shiny gold star for the day.