Issue when calling an external web service - CRM 2013

Question

Hello everyone.
This is my scenario:
I'm doing a real time data integration from CRM to another software. I deployed several plugins, mostly in create/update messages, for the entities i want to sync. The developers of the other software gave me the endpoint of the web service and I created the
client using svcutil. I manually created the binding and gave it to the generated client, along with the endpoint. At the first tests I could sync some registries, but I had some mapping errors. I debugged the plugin, corrected the errors, and when I
want to tests again, the plugin is throwing me an exception when calls any method of the web service. Let me explain the issue:
The exception:
I instantiated the client for the web service (passing to it the binding and the endpoint). And when I'm trying to call any method (ex. Add), it throws the exceptions "InvalidOperationException". I started to debug the code and I notice that
just before to call the web service method, the state of the client stills in "Opening". Of course that is generating the exception. 
The complete exception is: "The communication object, System.ServiceModel.ChannelFactory`1[IAxxisWcfServices], cannot be modified while it is in the Opening
state."} System.SystemException {System.InvalidOperationException}
I did a test, outside the CRM environment, on a console app with the same conditions of the web services client (generating with svcutil, manually passing the same binding and endpoint), and the same order of the plugin code, and everything works well; The
state of the client never stills in 'Opening', so I discarded any problem with the web service.
Anyone knows if I'm missing something in the code? or some configuration?
The CRM is 2013 On-premise with last updates.
Thanks in advance.

Answer 1

I tried adding the web reference in a console app and works fine. In the plugins this can't be done, because the plugins are deploy in database.
I tried another basic test using ChannelFactory. Only want to retrieve some entity through the external web services:
IPluginExecutionContext context = localContext.PluginExecutionContext;
IOrganizationService service = localContext.OrganizationService;
ITracingService tracer = localContext.TracingService;
try
BasicHttpBinding binding = new BasicHttpBinding();
binding.Name = "BasicHttpBinding_IAxxisWcfServices";
binding.Security.Mode = BasicHttpSecurityMode.None;
binding.Security.Transport.ProxyCredentialType = HttpProxyCredentialType.None;
binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.None;
EndpointAddress endpoint = new EndpointAddress(@"http://*****.svc");
ChannelFactory<IAxxisWcfServices> factory = new ChannelFactory<IAxxisWcfServices>(binding, endpoint);
IAxxisWcfServices channel = factory.CreateChannel();
var entity = channel.FindByEntities(new CRM.Application.Context.Dtos.Asegurado( { CrmGuid = "7C3E96C6-C3BC-E411-80DF-0A736AE14667" }, null, new CRM.Framework.Session() { User = "***", Password = "***" });
catch (Exception ex)
throw new InvalidPluginExecutionException(ex.Message);
That test threw the following exception on the GenericParameterAttributes of channelType of factory object:
http://s27.postimg.org/4wf3er8up/Error.png