// Create the binding.
WSHttpBinding myBinding = new WSHttpBinding();
myBinding.Security.Mode = SecurityMode.None;
myBinding.Security.Transport.ClientCredentialType =
HttpClientCredentialType.Basic;

myBinding.Name = "Remessa";

myBinding.Namespace = "cramg.cra21.com.br";
myBinding.AllowCookies = true;

EndpointAddress ea = new
EndpointAddress("http://cramg.cra21.com.br/cramg/xml/protestos.php");

CRAMG.servercraPortTypeClient t =
                           new CRAMG.servercraPortTypeClient(myBinding, ea);

t.ClientCredentials.UserName.UserName = "cromg";
t.ClientCredentials.UserName.Password = "
t.Open();
t.Remessa("tfasd", "fasfa");

br.com.cra21.cramg.servercra a = new br.com.cra21.cramg.servercra();
System.Net.CredentialCache myCredentials = new System.Net.CredentialCache();
a.UserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1)";
NetworkCredential netCred = new NetworkCredential("cromg", "1234");
myCredentials.Add(new Uri(a.Url), "Basic", netCred);
a.Credentials = myCredentials;
a.UseDefaultCredentials = false;
string retorno = a.Homologadas("2");

var client = new ServiceReference1.servercraPortTypeClient();
    client.ClientCredentials.UserName.UserName = "name";
    client.ClientCredentials.UserName.Password = "password";

    client.Homologadas("2");

    client.Close();

<configuration>
    <system.serviceModel>
        <bindings>
            <basicHttpBinding>
                <binding name="server.craBinding" />
            </basicHttpBinding>
        </bindings>
        <client>
            <endpoint address="http://cramg.cra21.com.br/cramg/xml/protestos.php"
                binding="basicHttpBinding" bindingConfiguration="server.craBinding"
                contract="ServiceReference1.servercraPortType" name="server.craPort" />
        </client>
    </system.serviceModel>
</configuration>

public class serverBasicAuthentication : br.com.cra21.cramg.servercra
    {
        protected override WebRequest GetWebRequest(Uri uri)
        {
            HttpWebRequest request = (HttpWebRequest) base.GetWebRequest(uri);
            if (PreAuthenticate)
            {
                NetworkCredential networkcredential = base.Credentials.GetCredential(uri,"Basic");
                if (networkcredential != null)
                {
                    Byte[] credentialBuffer = new UTF8Encoding().GetBytes(networkcredential.UserName + ":" + networkcredential.Password);
                    request.Headers["Authorization"] = "Basic " + Convert.ToBase64String(credentialBuffer);
                }
                else
                   throw new ApplicationException("No network credentials") ;
            }
            return request;
        }
    }