Interactive calling over 5G – how does it work?

5G is being deployed, and new user values include higher data-speeds and low latency services for consumers, businesses and industries on smartphones and many other types of devices. But 5G also means that today’s mobile voice service could change radically. This is achieved with the Ericsson innovation concept ‘interactive calling’ which is built on IMS data channels. Find out how this works in a 5G network.

Man in Robot factory using AR
Jan 20, 2020
Mattias Dahlquist 

Principal System Architect and Chief Architect for IMS

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My colleague wrote two blog posts in 2019 about interactive calling and how consumers, businesses and society could benefit from this type of service in future 5G voice-enabled networks. If you missed these posts, you can find them here:

Evolve VoLTE to enable real-time interaction over 5G with IMS data channel

Interactive calling: A new experience for 5G smartphones

As Principal System Architect and Chief Architect for IMS, my current focus is on how to evolve our communication experience when moving towards 5G. In this blog post, I’d like to share some technical details behind the interactive calling concept. This is our innovation idea for how to move from basic voice communication to an interactive communication experience by combining standard telecom/IMS technologies with web technologies.

Ericsson’s interactive calling leverages the VoLTE (voice over LTE) service and network capabilities for 5G. It enables a real-time communication to real-time interaction evolution, combining an HD voice call and a video call with capabilities to remotely interact with other humans or machines.

This new concept was proposed to the 3GPP standardization for 5G in 2019 and is currently being discussed within the standardization fora. In parallel, Ericsson is continuing to engineer the technical details of the solution. Whilst it is not yet commercially available, I can already explain the main technology behind this innovation. However, to make this a fully commercial 5G service, it will take time to implement all the technical details within networks and devices and align them with standardization guidelines.


Interactive calling is built on IMS data channels

Interactive calling uses existing industry standards (3GPP) and specifications for VoLTE (GSMA IR.92) and ViLTE (GSMA IR.94), and builds on WebRTC standards, therefore combining telco assets with web technologies. The network capabilities (for example, QoS, robustness, and low latency) of 5G Core and 5G Radio Access Networks are a prerequisite. 

Existing VoLTE deployments enable an HD voice session that can be enhanced with a video calling session over LTE (ViLTE). The interactive calling concept builds on the existing VoLTE / ViLTE session by adding what is referred to as ‘data channels. These data channels are synchronized with the voice and video calling session. As a result, the user of the service is able to interact with another entity in real time using voice (VoLTE), video calling (ViLTE) and any type of desired interaction capability sent over the data channel (such as interactive screen-sharing or augmented reality overlay).

Interactive calling is built on IMS (IP Multimedia Subsystem) as IMS is the selected architecture and solution to provide voice and communication services over 4G and 5G. The benefit here is that service providers can build on and develop new services on top of the globally available voice networks they have already deployed. The inbuilt benefits of IMS, such as find-and-connect end-points using the globally routable phone numbers (MSISDN), quality-of-service, mobility, reliability, robustness, security, connectivity, charging of the service, regulatory requirements, and so on, are imperative to the success of interactive calling. For more advanced real-time interactive use cases like remote surgery or a mixed reality experience (incorporated with VoLTE / 5G voice and video calling), IMS quality-of-service mechanisms are even more important.


Interactive calling

Fig 1: High level overview of signaling in a 5G network to establish an IMS data channel for interactive calling


Interactive calling does not alter the existing IMS signaling principles defined in VoLTE. Additional information is added to the signaling to inform the network and the remote party that an IMS data channel is supported (and thus the ability to support interactive calling), as well as information to inform the network about what characteristics are needed for the specific data channel(s) to be established.

The additional information in the SIP signaling (to inform of data channel support) is the inclusion of a ‘data channel’ media feature tag in the session request. The information that informs the network of the requested characteristic for the data channel is carried in the Session Description protocol (SDP) and follows the principles outlined in existing WebRTC standards (IETF). The combination of IMS signaling with WebRTC data channel handling ensures the requested characteristics for the data channel are guaranteed in the same way as for voice and video communication over LTE, 5G Core and the radio access network.

When IMS was introduced to standards at the beginning of the century, it came with a vision to be an all IP communication engine for any device, over any access, for any service. Even if the IMS technology was selected as the telephony solution for 4G (VoLTE), the service experience has been kept very similar to the old circuit switched voice services. Now, when a global IMS ecosystem has, and is, being established, it’s time to level up to what IMS once promised: to become the communication engine for a full interactive communication experience.

Would you like to know more about the IMS data channel technology and how this would work in a 5G network?

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