diff --git a/protocol-spec/account-registration.md b/protocol-spec/account-registration.md
new file mode 100644
index 0000000..7daf529
--- /dev/null
+++ b/protocol-spec/account-registration.md
@@ -0,0 +1,103 @@
+# Account registration
+## Introduction
+This extension is intended for creating user accounts on a server  
+
+## Message type identifiers
+- `profile:register`    
+
+## Error codes
+- 0: limit exceed
+- 1: username/third party ID already taken
+- 2: registration isn't allowed on a server
+
+## Use cases
+- Request:
+```json
+{
+    "id": "abcd",
+    "type": "profile:register",
+    "to": "cadmium.org",
+    "payload": {
+        "username": "juliet",
+        "thirdPIDs": [
+            {"type":"email", "value":"juliet@capulett.com"},
+            {"type":"msisdn", "value":"+1234567890"},
+        ],
+        "password": "romeo1"
+    }
+}
+```
+
+- Response:
+```json
+{
+    "id": "abcd",
+    "type": "profile:register",
+    "from": "cadmium.org",
+    "ok": true,
+    "payload": {
+        "userID": "@juliet@cadmium.org"
+    }
+}
+```
+
+*<b>Error</b> response*:
+```json
+{
+    "id": "abcd",
+    "type": "profile:register",
+    "from": "cadmium.org",
+    "ok": false,
+    "payload": {
+        "errCode": 1,
+        "errText": "{Username/email/msisdn} already taken"
+    }
+}
+```
+
+## Business Rules
+None.
+
+## JSON Schema
+**Payload**
+
+- Request:
+```typescript
+interface RegistrationRequestPayload {
+    /**
+     * The username that the user wants to register
+     */
+    username: string,
+
+    /**
+     * Array of user third party IDs (email and/or MSISDN)
+     */
+    thirdPIDs: ThirdPartyID[],
+
+    /**
+     * Password of new account
+     */
+    password: string
+}
+
+interface ThirdPartyID {
+    /**
+     * Type of third party ID
+     */
+    type: string,
+
+    /**
+     * String contains third party ID. Examples: "juliet@capulett.com", "+1234567890".
+     */
+    value: string
+}
+```
+- Response:
+```typescript
+interface RegistrationResponsePayload {
+    /**
+     * ID of user (Username in priority. If we haven't username, then we put to this field one of user's third party IDs)
+     */
+    userID: EntityID
+}
+```
\ No newline at end of file
diff --git a/protocol-spec/core.md b/protocol-spec/core.md
index c005508..334cda3 100644
--- a/protocol-spec/core.md
+++ b/protocol-spec/core.md
@@ -7,7 +7,6 @@
   - [Errors](#errors)
   - [User devices](#user-devices)
   - [Account registration/login](#account-registrationlogin)
-    - [Create account](#create-account)
     - [Login into account (by username)](#login-into-account-by-username)
 
 ## Transport
@@ -128,103 +127,6 @@ interface ErrorPayload {
 `todo`
 
 ## Account registration/login
-### Create account
-**Description**: Create user account on a server  
-**Type**: `profile:register`    
-**Payload**:
-- Request:
-```typescript
-interface RegistrationRequestPayload {
-    /**
-     * The username that the user wants to register
-     */
-    username: string,
-
-    /**
-     * Array of user third party IDs (email and/or MSISDN)
-     */
-    thirdPIDs: ThirdPartyID[],
-
-    /**
-     * Password of new account
-     */
-    password: string
-}
-
-interface ThirdPartyID {
-    /**
-     * Type of third party ID
-     */
-    type: string,
-
-    /**
-     * String contains third party ID. Examples: "juliet@capulett.com", "+1234567890".
-     */
-    value: string
-}
-```
-- Response:
-```typescript
-interface RegistrationResponsePayload {
-    /**
-     * ID of user (Username in priority. If we haven't username, then we put to this field one of user's third party IDs)
-     */
-    userID: EntityID
-}
-```
-
-**Errors**:
-- 0: limit exceed
-- 1: username/third party ID already taken
-- 2: registration isn't allowed on a server
-
-**Usecase**:
-
-*Request*:
-```json
-{
-    "id": "abcd",
-    "type": "profile:register",
-    "to": "cadmium.org",
-    "payload": {
-        "username": "juliet",
-        "thirdPIDs": [
-            {"type":"email", "value":"juliet@capulett.com"},
-            {"type":"msisdn", "value":"+1234567890"},
-        ],
-        "password": "romeo1"
-    }
-}
-```
-
-*Response*:
-```json
-{
-    "id": "abcd",
-    "type": "profile:register",
-    "from": "cadmium.org",
-    "ok": true,
-    "payload": {
-        "userID": "@juliet@cadmium.org"
-    }
-}
-```
-
-*<b>Error</b> response*:
-```json
-{
-    "id": "abcd",
-    "type": "profile:register",
-    "from": "cadmium.org",
-    "ok": false,
-    "payload": {
-        "errCode": 1,
-        "errText": "{Username/email/msisdn} already taken"
-    }
-}
-```
-
-**Special business rules**: none.
 
 ### Login into account (by username)
 **Description**: Login into user account on a server by username