Next Generation eCall Finally Moves to 4G and 5G

Back in 2022, I wrote about the transition from the original eCall system to Next Generation eCall, or NG eCall. At the time, one of the big concerns was what would happen to millions of vehicles relying on 2G and 3G as mobile operators gradually switched off these legacy networks.

Four years later, the transition is no longer something happening in the distant future. 2026 is an important year for NG eCall in Europe.

For anyone unfamiliar with eCall, it is the European emergency calling system built into vehicles. Following a serious accident, the vehicle can automatically call the European emergency number 112, or the call can be triggered manually. Along with establishing a voice connection, the vehicle sends a Minimum Set of Data (MSD) containing information such as its location, direction of travel and other relevant vehicle information. eCall has been required for new M1 and N1 vehicle types in the EU since April 2018.

The problem is that the original eCall architecture was designed around circuit-switched 2G and 3G networks. The MSD is transferred using an in-band modem during the emergency voice call.

NG eCall takes a different approach. It uses packet-switched connectivity and IMS, allowing eCall to operate over 4G LTE and 5G. At the protocol level, it becomes an IMS emergency call, with SIP used for call signalling and the eCall MSD carried as emergency-call data within the SIP-based session.

This transition became much more significant on 1 January 2026. From that date, new M1 and N1 vehicle types in the EU have to support packet-switched eCall. Public Safety Answering Points (PSAPs) that were already deployed are also required to support eCall over packet-switched 4G/5G networks from the beginning of 2026.

The standards have continued to evolve as well. Commission Delegated Regulation (EU) 2025/1871 updated the regulatory references to the newer EN 17184:2024, covering eCall high-level application protocols using IMS over packet-switched networks, and EN 17240:2024, covering end-to-end conformance testing. There are transitional arrangements during 2026, with the newer EN standards becoming mandatory for new type approvals from 1 January 2027.

There is also evidence that the ecosystem is moving from specifications to actual interoperability testing. In June 2026, ETSI organised its latest NG eCall Plugtests in Ljubljana. Testing focused on interoperability between In-Vehicle Systems (IVS) and PSAPs over 4G LTE, and importantly included access to a real Telekom Slovenije mobile network rather than relying entirely on simulated infrastructure. Testing used ETSI TS 103 683, with EN 17240:2024 conformance testing also supported.

However, moving new vehicles to NG eCall does not make the legacy problem disappear.

The existing European vehicle fleet contains a very large number of cars whose eCall systems still depend on 2G/3G. EU rules therefore require PSAPs to continue supporting circuit-switched eCall while at least one circuit-switched mobile network remains operational in the relevant Member State.

A European Commission Joint Research Centre study published in May 2026 highlights the scale of the challenge. Its modelling estimates that there could still be around 66.8 million passenger vehicles equipped with circuit-switched eCall at the end of 2027. The study considers several possible mitigation approaches, including upgrading suitable existing eCall units to 4G, using 4G-capable third-party eCall systems and providing aftermarket solutions for vehicles that cannot otherwise be upgraded.

So, in some ways, we now have two parallel eCall transitions taking place. New vehicles and emergency infrastructure are moving towards IMS-based NG eCall over 4G and 5G, while the industry still has to work out how to keep tens of millions of older vehicles able to contact emergency services as 2G and 3G networks disappear.

The short Rohde & Schwarz video below provides a good overview of how eCall and NG eCall work, followed by an explanation of how the technology can be tested from the GNSS module and telematics control unit (TCU) through to complete vehicle-level testing.

Voice over New Radio (VoNR) Establishment and Release between NG RAN and 5G Core

In this video I explain how QoS Flows for VoNR are established and released especially on N2 reference point between 5G Core and NG RAN.

The pervious video about generic aspects of "QoS Flow Establishments in 5G Standalone RAN and Core" you will find in the first link of the Related Posts listed below:

Related Posts: 

• The 3G4G Blog: QoS Flow Establishments in 5G Standalone RAN and Core
• The 3G4G Blog: Anomaly Detection and other AI Algorithms in RAN Optimization
• The 3G4G Blog: How to Identify Network Slices in NG RAN
• The 3G4G Blog: Network Slicing in NG RAN
• The 3G4G Blog: Network Slicing Tutorials and Other Resources
• The 3G4G Blog: Artificial Intelligence (AI) / Machine Learning (ML) in 5G Challenge by ITU
• The 3G4G Blog: Conditional Handover (Rel. 16) Explained
• The 3G4G Blog: UE Radio Capability Signaling Optimization (RACS) in Rel. 16 

Presentation: IMS for 3G Voice Services and Migration Strategies

Very interesting presentation from NTT DoCoMo in the IMS workshop I blogged about yesterday. It shows their strategy to move from legacy core network to an All IP Network (AIPN).

IMS for 3G Voice Services and Migration Strategies

View more presentations from Zahid Ghadialy.

SS7, IMS, SIP and Diamater

Going through my pile of 1 million things to read before I die, I came across this presentation by Tekelec with regards to why Diamater and SIP would be used instead of SS7 in LTE and IMS. The slide in the picture above shows the comparison of SS7 and Diamater.

More and more operators are asking for replacement of SS7 with the Diamater interface. The main reason being that it has been adopted by 3GPP and when we move to an all IP network as in case of LTE it makes sense to have Diamater instead of SS7. There is a good description of Diameter on Wikipedia (cant guarantee the accuracy though) here.

You can read more about SIP at the Tekelec blog here.

There is also an interesting Radvision presentation on Slideshare that I have embedded below:

IMS strategies: Synopsis from IMS 2.0 world forum

From Ajit's Open Gardens Blog:

IMS 2.0 world forum is a must attend event .. I learnt a lot from it. Here is a brief synopsis of where I see IMS is heading to ..

Seek your thoughts and feedback especially you can identify other Operators with an interesting strategy and / or if you attended this event

As I could gather, there are six broad strategies:
a) Voice call continuity(VCC) / fixed to mobile convergence
b) Blended voice : voice tied contextually to messaging or rich media
c) SIP without IMS (Naked SIP)
d) Strategies from device manufacturers(especially Nokia and Motorola)
e) Real time IMS applications (multiplayer games and other such applications that need near real time blended media interaction within a session)
f) Abstraction of the core network

Most of the focus is around (a) Voice call continuity(VCC) / fixed to mobile convergence

This is a pity – but also understandable Operators are most familiar with voice
In its broadest sense, voice call continuity pertains to roaming within cellular and non cellular networks(such as roaming between cellular and wifi networks). A specific instance of this is Fixed to mobile convergence for instance BT fusion

My personal view is:

a) I don’t quite know if I would be interested in FMC as a customer ..
b) I think its being sold on cost – which is not a good idea
c) I think it fulfils an industry goal(fixed and mobile networks trying to get new subscribers from each other’s networks in mature markets)
d) In general, voice is becoming cheap .. so I am not sure that a pure voice play is a good idea

Blended voice(b) and real time applications(e) are interesting but need device support. Devices supporting IMS fully are conspicuous by their absence!

In contrast, devices supporting SIP(c) - but not IMS are very much here and so are applications – for instance movial

Abstracting the network layer through software APIs(f) – is the most interesting – but I felt very few Operators had the vision to embrace this strategy at the moment. The two big exceptions being TIM and Telia sonera - who are doing some very interesting work.

To recap, by abstracting the network layer, I mean : In an IP world, as the Mobile Internet mirrors the Internet, the Operator should focus on the core of the network and leave the edge of the network to third parties. Specifically, this means – identify the elements that can be performed ONLY in the core and then abstract them through APIs. This approach gets us away from the dichotomy of the ‘pipe’ vs. ‘no pipe’. It also means that the Operator retains control.

Finally, Operators in emerging markets like Globe telecom from Philippines were also impressive i.e. they understood the space, the issues specific to their market and how they could leverage IMS in their markets. Harvey G Libarnes, Head of innovation and incubations program , Globe Telecom, gave a very thorogh presentation

Finally, there are some interesting plays : such as Mobilkom with A1 over IP and France Telecom with IPTV strategy

To conclude:
a) At Operator level, IMS is still largely about voice and a defensive approach(such as FMC)
b) Lack of devices is the key question mark
c) Device manufacturers on the other hand have significant leverage(more on that soon)
d) Some operators are going to be very innovative – TIM and Teliasonera from amongst the attendees