Advantages of VoLTE | Disadvantages of VoLTE | Voice Over LTE

This page covers advantages and disadvantages of VoLTE. It mentions VoLTE advantages or benefits and VoLTE disadvantages or drawbacks. VoLTE stands for Voice Over LTE.

What is VoLTE?

The LTE is all IP network designed for internet/data applications. To support voice over LTE network there are two options viz. using IMS (VoIP) and circuit switched legacy fall back on 2G/3G.

VoLTE is HD voice calling service over 4G/LTE network rather than 2G/3G network.

VoLTE using VOIP through IMS

VoLTE using IMS(VOIP):
• If it is VOIP to VOIP call, it will remain within LTE network and supported using VOIP protocols.
• But if it is VOIP to CS call for GSM/WCDMA network, IMS with the help of application servers and legacy MSC transfers the PS call to legacy networks (2G-GERAN/3G-UTRAN).
• If it is VOIP to PSTN call, IMS directs through PSTN interface to respective exchanges.


VoLTE using 2G/3G CSFB(using SRVCC):
• When UE moves from LTE network to say legacy networks(GSM/WCDMA), based on measurement report submitted by UE handover is performed and transfer of Voice over IP call to legacy voice call is performed.


Refer VoLTE basics >>, VoLTE Call Flow Procedure >> and VoLTE UE attach procedure >> for more information.

Advantages of VoLTE

Following are the advantages of VoLTE:
➨It delivers all voice and data services over same network. Hence it does not require to maintain legacy infrastructure.
➨VoLTE make calls much faster compare to 2G/3G voice calls.
➨It offers better security and QoS (Quality of Service) compare to legacy 2G/3G networks.
➨It extends life of battery used in smart phones. This is due to use of shorter DRx which results into improvement in device power efficiency.
➨It increases functionalities of VoIP protocols.
➨It offers improvement in capacity using RoHC/SPS protocols.
➨It provides call continuity between packet switched LTE network and circuit switched WCDMA network using SVRCC (Single Radio Voice Call Continuity).
➨It improves UL coverage using TTI bundling.
➨All the profiles are GSMA defined and hence it is compatible across the world. This leads to easy roaming, availability of handsets etc.

Disadvantages of VoLTE

Following are the disadvantages of VoLTE:
➨It requires investment in network wide IMS. Hence this will not be available everywhere and hence roaming could be challenge for sometime.
➨If there is no data connection or 4G signaling in the area, user will neither be able to call nor able to use internet using handset.
➨VoLTE should be supported by handsets in order to obtain VoLTE services. The VoLTE feature is not available in all the mobile handsets.
➨HD voice call can only be made between two VoLTE compliant handsets. If VoLTE handset calls any other network compliant handset the standard call quality can be achieved and not HD quality.

Also refer advantages and disadvantages of VOIP>>.

VoLTE Related Links

LTE to VoLTE converter
Voice over LTE basics
echo canceller
exchange signaling types
EPABX basics

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