Реализован вход в систему в IntersvyazClient.

src/Intersvyaz.Net/JsonContent.cs

@@ -0,0 +1,20 @@
+using System.Text;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
+using System.Net.Http;
+
+namespace Intersvyaz.Net
+{
+    public class JsonContent : StringContent
+    {
+        public JsonContent(object value) : base(Serialize(value), Encoding.UTF8, "application/json") { }
+
+        private static string Serialize(object value)
+        {
+            return JsonConvert.SerializeObject(value, Formatting.None, new JsonSerializerSettings()
+            {
+                ContractResolver = new CamelCasePropertyNamesContractResolver(),
+            });
+        }
+    }
+}