voice over LTE (VoLTE)

Voice over LTE (VoLTE) is a digital packet technology that uses 4G LTE networks to route voice traffic and transmit data. This voice service is the standard for high-speed wireless communications in devices such as smart phones, data terminals, IoT devices and wearables.

VoLTE is important for network operators, vendors, original equipment manufacturers (OEM) and consumers. Since LTE is a data-only networking technology, VoLTE provides higher quality calls, better service and the ability to simultaneously use voice and data.

How does VoLTE work?

VoLTE is based on the IP Multimedia Subsystem (IMS) framework. This allows the service to deliver multimedia as data flows using a common IP interface that can utilize but does not depend on a legacy circuit-switched voice network.

For example, a user may initiate a call using the LTE network. However, if they wander outside of an LTE coverage area, the call will go back to the legacy network. This functionality is referred to as Single Radio Voice Call Continuity (SR-VCC), where two connections are simultaneously maintained until the LTE signal is lost.

Additionally, the recommended speech codec for VoLTE is adaptive multi-rate wideband (AMR-WB), or HD voice. HD voice increases the audio frequency range for voice calls and raises sound quality.

Support for VoLTE

Most 4G wireless networks use LTE technology and thus support VoLTE. At the beginning of 2019, over 253 network operators were investing in VoLTE technology with 137 of them offering VoLTE services. Most cellular devices have VoLTE capabilities including any iPhone after the iPhone 6, all Google Pixel models and Samsung Galaxy models after 2015.

In order to make a VoLTE call, both devices involved in the communication must be compatible with VoLTE, located in a supported area and have their capabilities set to on. Users also have the option to toggle VoLTE on and off through the device settings.

Benefits of VoLTE

VoLTE can provide service providers and device users with multiple benefits, including:

  • Uses the spectrum more efficiently than traditional voice.
  • Increases battery life when compared to VoIP.
  • Provides a superior audio quality and a clearer calling experience.
  • Offers more reliable services and interoperability.
  • Lets users make calls and use data simultaneously.
  • Allows up to six-way conference calls.
  • Can be deployed along with multimedia services such as video sharing and multimedia messaging.
  • Simplifies network management and developer accessibility.
  • Frees up network bandwidth due to a smaller packet.
This was last updated in August 2019

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