diff --git a/src/Intersvyaz.Net/Class1.cs b/src/Intersvyaz.Net/Class1.cs
deleted file mode 100644
index a7c29d5..0000000
--- a/src/Intersvyaz.Net/Class1.cs
+++ /dev/null
@@ -1,8 +0,0 @@
-using System;
-
-namespace Intersvyaz.Net
-{
-    public class Class1
-    {
-    }
-}
diff --git a/src/Intersvyaz.Net/Intersvyaz.Net.csproj b/src/Intersvyaz.Net/Intersvyaz.Net.csproj
index b290d67..d4cb484 100644
--- a/src/Intersvyaz.Net/Intersvyaz.Net.csproj
+++ b/src/Intersvyaz.Net/Intersvyaz.Net.csproj
@@ -4,4 +4,8 @@
     <TargetFramework>netstandard1.4</TargetFramework>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.4" />
+  </ItemGroup>
+
 </Project>
diff --git a/src/Intersvyaz.Net/IntersvyazClient.cs b/src/Intersvyaz.Net/IntersvyazClient.cs
new file mode 100644
index 0000000..5ab752c
--- /dev/null
+++ b/src/Intersvyaz.Net/IntersvyazClient.cs
@@ -0,0 +1,67 @@
+using System;
+using System.Linq;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Threading.Tasks;
+using Intersvyaz.Net.Models;
+using Newtonsoft.Json;
+
+namespace Intersvyaz.Net
+{
+    public class IntersvyazClient
+    {
+        private readonly Uri BASE_ADDRESS = new Uri("https://api.is74.ru");
+
+        private HttpClient httpClient;
+
+        public IntersvyazClient()
+        {
+            httpClient = new HttpClient()
+            {
+                BaseAddress = BASE_ADDRESS,
+            };
+
+            // TODO: Добавить здесь ссылку на репозитории.
+            httpClient.DefaultRequestHeaders.UserAgent.Add(
+                new ProductInfoHeaderValue("Intersvyaz.Net", "1.0"));
+        }
+
+        public IntersvyazClient(string token) : base()
+        {
+            httpClient.DefaultRequestHeaders.Authorization
+                = new AuthenticationHeaderValue("Bearer", token);
+        }
+
+        public async Task<LoginResponseDto> Login(string username, string password)
+        {
+            var content = new JsonContent(new LoginRequestDto()
+            {
+                Username = username,
+                Password = password,
+            });
+
+            using (var message = await httpClient.PostAsync("/auth/mobile", content))
+            {
+                var data = await message.Content.ReadAsStringAsync();
+
+                if ((int)message.StatusCode == 422) // NOTE: Data Validation Error
+                {
+                    var errors = JsonConvert.DeserializeObject<ValidationErrorDto[]>(data);
+                    throw new InvalidOperationException(string.Join("; ", errors.Select(e => e.Message)));
+                }
+
+                if (!message.IsSuccessStatusCode)
+                {
+                    throw new InvalidOperationException("Неизвестная ошибка сервера");
+                }
+
+                var result = JsonConvert.DeserializeObject<LoginResponseDto>(data);
+
+                httpClient.DefaultRequestHeaders.Authorization =
+                    new AuthenticationHeaderValue("Bearer", result.Token);
+
+                return result;
+            }
+        }
+    }
+}
diff --git a/src/Intersvyaz.Net/JsonContent.cs b/src/Intersvyaz.Net/JsonContent.cs
new file mode 100644
index 0000000..223f798
--- /dev/null
+++ b/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(),
+            });
+        }
+    }
+}
diff --git a/src/Intersvyaz.Net/Models/LoginRequestDto.cs b/src/Intersvyaz.Net/Models/LoginRequestDto.cs
new file mode 100644
index 0000000..ba9f567
--- /dev/null
+++ b/src/Intersvyaz.Net/Models/LoginRequestDto.cs
@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Intersvyaz.Net.Models
+{
+    public class LoginRequestDto
+    {
+        public string Username { get; set; }
+
+        public string Password { get; set; }
+    }
+}
diff --git a/src/Intersvyaz.Net/Models/LoginResponseDto.cs b/src/Intersvyaz.Net/Models/LoginResponseDto.cs
new file mode 100644
index 0000000..2468be5
--- /dev/null
+++ b/src/Intersvyaz.Net/Models/LoginResponseDto.cs
@@ -0,0 +1,41 @@
+using System;
+using Newtonsoft.Json;
+
+namespace Intersvyaz.Net.Models
+{
+    public class LoginResponseDto
+    {
+        [JsonProperty("USER_ID")]
+        public long UserId { get; set; }
+
+        [JsonProperty("PROFILE_ID")]
+        public long? ProfileId { get; set; }
+
+        [JsonProperty("APP")]
+        public string Application { get; set; }
+
+        [JsonProperty("ACCESS_BEGIN")]
+        public DateTime AccessBegin { get; set; }
+
+        [JsonProperty("ACCESS_END")]
+        public DateTime AccessEnd { get; set; }
+
+        [JsonProperty("TOKEN")]
+        public string Token { get; set; }
+
+        [JsonProperty("AUTH_TYPE")]
+        public string AuthenticationType { get; set; }
+
+        [JsonProperty("UNIQUE_DEVICE_ID")]
+        public string UniqueDeviceId { get; set; }
+
+        [JsonProperty("PHONE")]
+        public int Phone { get; set; }
+
+        [JsonProperty("LAST_CHECK_DATE")]
+        public DateTime LastCheckTime { get; set; }
+
+        [JsonProperty("ACCESS_END_LEFT")]
+        public long AccessEndLeft { get; set; }
+    }
+}
diff --git a/src/Intersvyaz.Net/Models/ValidationErrorDto.cs b/src/Intersvyaz.Net/Models/ValidationErrorDto.cs
new file mode 100644
index 0000000..bacfc18
--- /dev/null
+++ b/src/Intersvyaz.Net/Models/ValidationErrorDto.cs
@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Intersvyaz.Net.Models
+{
+    public class ValidationErrorDto
+    {
+        public string Field { get; set; }
+
+        public string Message { get; set; }
+    }
+}