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Lara Barboza September 17, 2020 0 Comments

The lack of automated and standardized VoLTE device configuration functionalities has slowed down the adoption of the Voice over LTE service for several years. VoLTE Device Entitlement Server (DES) is a network functionality, which solves the configuration problems. Here is an overview of VoLTE Device Entitlement… 

What is Voice over LTE, VoLTE?

The acronym VoLTE stands for Voice over LTE. As the name suggests, VoLTE technology provides IP based voice calls over a 4G LTE (Long Term Evolution) network. VoLTE technology is based on the IP Multimedia Subsystem (IMS) network. VoLTE technology specification is defined by GSMA in PRD IR.92.

LTE networks are based on IP packet-switching technology, thus VoLTE calls are delivered as data flows within the LTE data bearer; as opposed to the 2G or 3G networks where voice calls are based on the circuit switching technology.

VoLTE technology, or Voice over LTE is slowly gaining momentum in the market. According to GSMA, there are 165 mobile operators which have launched VoLTE until 1Q in 2019. This is 23% more operators compared to the situation in one year ago, when there were 127 VoLTE networks. At the same time, 702 operators operate a LTE network.

More than 2,000 VoLTE Phone Models

Most of the 4G LTE capable mobile phones and smartphones provide support for VoLTE calls. Currently there are more than 2,000 VoLTE capable phones registered in the market. The list of Top 25 VoLTE phones shows you the most popular device models with VoLTE support found by Sicap’s VoLTE phone study in January in 2019.

Complex VoLTE Device Configuration has been the Roadblock for Growth!

A major obstacle for the proliferation of VoLTE calling has been the lack of automated device configuration functionalities. Without the correct service configuration, VoLTE phones cannot connect correctly to the operators’ VoLTE network.

Due to the lack of automated VoLTE device configuration, those operators who launched VoLTE have had to carry out time consuming device firmware customization process with the manufacturers to hard code the VoLTE and RCS settings in devices.

Extensive network configuration and testing have been required to tune up their networks to support a limited selection of VoLTE handset models. Also, the IMS networks have had to be hard coded to support specific firmware versions of those handsets.

Reconfiguration and testing was required in the case of handset operating system or firmware updates. End-users have been required to master complex VoLTE settings on their devices. All this have resulted in slowed down service adoption.

Device Entitlement is the VoLTE Solution!

VoLTE Device Entitlement Server (DES) is a telecom network functionality, which solves the VoLTE handset configuration problems described earlier by introducing an automated device and subscriber authentication functionality and an over-the-air configuration for the service settings. The services include Voice over LTE (VoLTE), Video over LTE (ViLTE),Voice over WiFi and Rich Communications Service (RCS).

How VoLTE Benefits from Automated Device Entitlement?

  • Authentication of Subscribers and Devices
  • Automatic and up-to-date VoLTE device configuration. No network changes needed.
  • Simplification saves costs in VoLTE deployment, operations and maintenance
  • Frictionless VoLTE user-experience speeds up service adoption
  • Full VoLTE roaming coverage enabled

GSMA has Standardized VoLTE Device Entitlement

There are multiple entitlement methods and standards. Google Android and Microsoft Windows Mobile have implemented device entitlement according to GSMA’s next generation communication services standards.

The GSMA standards related to VoLTE Device Entitlement are listed here:

Apple Entitlement Protocol

Apple have opted for a proprietary device entitlement process for iOS devices. This blog describes the GSMA specified entitlement standard.

What does Device Entitlement mean?

Entitlement is a functionality in a mobile network to inform a mobile device about which service capabilities the device owner can use with his or her carrier. It enables the device to enforce access only to the allowed services.

Registration feature allow devices with proprietary messaging protocols to register themselves automatically with the subscriber information, without relying on SMS messages.

Why Device and User Authentication is Needed?

As IMS is a fully IP-based system, any device can attempt to connect to it. One of the key features of the Device Entitlement Server is to enforce device and user authentication and to activate the right, allowed services and features. Because of this, Device Entitlement Server requires an integration with a carrier’s AAA, DRA and the PCEF servers.

BSS Integration Needed for Subscriber Profile

Device Entitlement Server needs to integrate with a carrier’s Business Support System (BSS) to fetch subscriber profile information based on which correct services can be activated on mobile devices during the entitlement process.



Here is the Standard VoLTE Entitlement Process 


In the simplest variant of the GSMA specified entitlement process, the authentication of the primary device is based on AAA server integration (Radius or Diameter) or HTTP header enrichment information. The authentication is carried out through two HTTP(S) requests.

The authentication procedure is followed by the VoLTE device configuration, which completes the entitlement process and the user can start using the VoLTE services.

Step by Step VoLTE Entitlement

The Process for VoLTE Device Entitlement with One Time Password Authentication

The GSMA and RCS specifications provide an enhanced, SMS based One Time Password (OTP) authentication procedure, which can be implemented for devices supporting it.

In the SMS based OTP process, Device Entitlement Server retrieves the MSISDN through a HTTP request and sends a “One Time Password” on a silent SMS to the device based on which the authentication is completed.

VoLTE Entitlement for Secondary Devices

Additionally, GSMA has specified authentication and entitlement mechanisms for secondary devices – as an example, the Open ID method, which enables authentication of secondary devices without a SIM card. The entitlement process for secondary devices will be described in detail in another blog.

How to Deploy the VoLTE Entitlement Solution?

Here is a simple five-step guide how you can deploy the VoLTE device entitlement on your network!

  1. Request device vendors to enable IMS client as the main phone application
  2. Device vendors create custom ROMs, which enable IMS and RCS provisioning
  3. Configure your DNS server to redirect HTTP entitlement requests to your Device Entitlement Server URL address
  4. Verify that the VoLTE phones are correctly provisioned
  5. Upon completed tests, the device entitlement solution is ready for launch

The below picture illustrates the VoLTE Device Entitlement Server integration layout in the IMS and RCS based entitlement scenario.

Step by step How to Deploy the VoLTE Entitlement Solution?

You can contact Sicap to find out the details about the authentication and entitlement procedure for Apple iOS devices, and for secondary devices such as smartwatches.

Download Sicap’s VoLTE Device Entitlement Server ebook for more information!

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