VoLTE – documents

Voice over Long Term Evolution (VoLTE) is the industry-recognised solution for providing a packet voice service, over IP via LTE access technology. VoLTE uses IMS technology, which provides a common platform to provide an enriched call experience by also deploying conversational video (ViLTE – Video over LTE) and RCS-based (Rich Communication Services) Enhanced Messaging.

2015 has seen increased deployments of VoLTE in Hong Kong, Japan, Singapore and the USA, with a large number of operators projected to deploy in 2016.

The GSMA has been actively engaged with the industry in relation to VoLTE deployments to gain further insight into trials, commercial deployments and live operations of the service. In this regard, the GSMA has published the VoLTE Service Description and Implementation Guidelines that describe VoLTE/ViLTE for single network, interconnect and roaming scenarios. The document also describes Single Radio Voice Call Continuity (SRVCC) (to provide seamless handover of voice calls from VoLTE to 2G/3G access) and intra-LTE Handover. See the GSMA PRD N2020.01, here.

In addition, the GSMA provides essential IP communications technical support, here. It contains the issues discovered during Interoperability Testing (IOT) and operators’ commercial deployments and related solutions to enable problem/knowledge sharing to facilitate VoLTE deployment. Users can raise issues anonymously which are related to VoLTE, ViLTE and RCS deployments and track progress of their resolution.

Related documents

A number of the GSMA’s Permanent Reference Documents (PRDs) regarding VoLTE, detailed below, are available for you to download here.

IR.92 (VoLTE) – IMS Profile for Voice and SMS

The IP Multimedia Subsystem (IMS) Profile for Voice and SMS, documented in this Permanent Reference Document (PRD), defines a profile that identifies a minimum mandatory set of features. These are defined in 3GPP specifications that a wireless device (the User Equipment [UE]) and network are required to implement in order to guarantee an interoperable, high quality IMS-based telephony service and IMS-based and SGs-based Short Message Service (SMS) over Long Term Evolution (LTE) radio access.

IR.94 (Video) – IMS Profile for Conversational Video Service

The IP Multimedia Subsystem (IMS) Profile for Conversational Video Service, documented in this Permanent Reference Document (PRD), defines a minimum mandatory set of features which are defined in 3GPP specifications that a wireless device and a network are required to implement to guarantee an interoperable, high quality IMS-based conversational video service over Long Term Evolution (LTE) radio access and/or High-Speed Packet Access (HSPA) radio access. The UE and the network may support the video service on either LTE or HSPA access or on both.

IR.34 – Guidelines for IPX Provider networks (Previously Inter-Service Provider IP Backbone Guidelines)

The Internet Protocol (IP) Packet eXchange (IPX) Network is an inter-service Provider IP backbone, which comprises the interconnected networks of IPX Providers and General Packet Radio Service (GPRS) Roaming eXchange (GRX) Providers. The purpose of this document is to provide guidelines and technical information on how these networks are set up and interconnect and how service providers will connect to the IPX Provider networks.

IR.39 – IMS Profile for High Definition Video Conference (HDVC) Service

The IP Multimedia Subsystem (IMS) Profile for High Definition Video Conference (HDVC) service, documented in this Permanent Reference Document (PRD), defines a minimum mandatory set of features that a video communication client and the network are required to implement to guarantee an interoperable, high quality IMS-based video communication service over fixed and mobile access.

IR.58 – IMS Profile for Voice over HSPA

The IP Multimedia Subsystem (IMS) Profile for Voice and SMS, documented in this Permanent Reference Document (PRD), defines a profile that identifies a minimum mandatory set of features which are defined in 3GPP specifications that a wireless device (the User Equipment [UE]) and network are required to implement in order to guarantee an interoperable, high quality IMS-based telephony service over High-Speed Packet Access (HSPA) radio access.

IR.64 – IMS Service Centralisation and Continuity Guidelines

The 3rd Generation Partnership Project (3GPP) has specified the solution for centralisation of services in the IP Multimedia Subsystem (IMS) and of IMS-based service continuity in Release 8 onwards. The user shall receive services in a consistent manner when the user accesses IMS either via the Circuit Switched (CS) or the Packet Switched (PS) domain. Service continuity is supported between CS and PS domains.

IR.65 – IMS Roaming and Interworking Guidelines

The 3rd Generation Partnership Project (3GPP) architecture has introduced a subsystem known as the IP Multimedia Subsystem (IMS) as an addition to the Packet-Switched (PS) domain. IMS supports new, IP-based multimedia services as well as interoperability with traditional telephony services. IMS is not a service per se, but a framework for enabling advanced IP services and apps on top of a packet bearer.

IR.67 – DNS/ENUM Guidelines for Service Providers and GRX/IPX Providers

Inter Service Provider IP communications are starting to evolve to support services other than GPRS Roaming. Many, if not all, of these services rely upon DNS. Therefore, it is of utmost importance for the interworking and stability of such services that service providers have all the necessary information to hand to ease configuration of their DNS servers upon which such services rely.

IR.88 – LTE Roaming Guidelines

This document aims to provide a standardised view on how Long-Term Evolution (LTE) and Evolved Packet Core (EPC) networks can interwork in order to provide “Next Generation Mobile Network” capabilities when users roam onto a network different from their HPMN. Expectations of the “Next Generation Mobile Network” capabilities are described in the GSMA Project Document: Next Generation Roaming and Interoperability (NGRAI) Project Scope White Paper.

NG.102 – IMS Profile for Converged IP Communications

This document defines a profile that identifies a minimum mandatory set of common IMS functionalities that are defined in 3GPP specifications and other GSMA PRDs that a wireless device (the User Equipment [UE]) and network are required to support in order to guarantee interoperable, high quality IMS-based and Mobile Operator provided Converged IP Communications Services (VoLTE, ViLTE, VoWi-Fi and RCS).

IR.95 – SIP/SDP Profile for inter-IMS NNI

This document describes a generic SIP/SDP profile for interconnection and roaming NNI between operators’ IMS networks for the purposes of exchanging traffic originating from and terminating to the respective operators’ customers. This document profiles SIP/SDP for the GSMA defined IMS based services ( i.e. VoLTE, ViLTE, VoWi-Fi, SMSoIP and RCS services).

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