# Step 3: Register SDK users

### API Reference

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## Introduction

This step plays a significant role in SDK installation. You have to register your app user on telematics platform and get devicetoken that you will add to the sdk. to register a user, you have to call **user service API**. 

DeviceToken **(Virtual device)** is a unique ID that belongs to a sure and it is used by sdk to transfer data to the platform.

Devicetoken = user

To obtain a DeviceToken you have to register users in is used as an identifier to link depersonalized telematics data with app user. 

## Integration options

there are several options for how you can register users. The final goal is to have Devicetoken in your database against the user record.

1. Register users from your mobile app and update user details by adding devicetoken
2. Register user from your back-end and store a devicetoken with user profile.

**User Service**, then keep the device token against a user account in your database.

![](/files/-MPzNfqi1EfkiCfeMOvY)

User service is a full-end service for user management. The main role of the service is to keep a unique user ID (Device Token) which used as a unique key to start collecting and transferring telematics data by telematics SDK. The service contains fields sufficient to build a full user profile if it is needed.

The rules of the service depend on a product selected in [SandBox](https://docs.userdatahub.com)

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**Telematics SDK.** no mandatory parameters. you can create a device token by a simple request without providing any parameters. However, we recommend to add some identifiers that you will use in DataHub to search users. if no paratemers provided, you will have in datahub a device token only. 
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**Platform.** Email or phone number are required. Given that the platform product is mainly used as a back-end service for mobile app, the parameters (email or phone number) will play a role of Login. However, we recommend adding more identifiers that you will use in DataHub to search users. if no parameters provided, you will have in datahub a device token and email or phone only. 
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