European roamers travelling in the USA this year may not have access to a voice service because of VoLTE compatibility/interoperability issues between networks and handsets. This means affected end-users will have no access to emergency services from their devices, a very serious public safety concern. It is not the time to sensationalise, apportion blame or become hyperbolic about this very serious risk. Cool heads and a collective effort are needed from all concerned stakeholders to fully understand the issues, to carefully assess the risks and to take the necessary steps to mitigate those risks in the short term, and ultimately, to resolve the issue.

Recent media reports have shone a spotlight on an emerging issue with potentially very serious public safety ramifications. European end-users, and end-users from other countries, heading to the USA this year may not be offered a voice service to make or receive calls by their roaming provider. This means that they may not be able to call their hotel, book a taxi, make a dinner reservation or call business associates, family or friends. They may also not be able to call emergency services on 911.

Over the last 10 years, the USA received around 11 million[1] annual visitors from Western Europe alone. As we emerge from the Covid crisis, this figure is likely to increase and this year will see a return to near-normal levels of business and leisure travel. Somewhere and at some point, a roaming end-user is going to need emergency assistance and they may not be able to call for it. This issue puts lives at risk. Public safety cannot be left to some kind of lottery with respect to the different capabilities of handsets and networks. One of the authors of this article recently travelled to the USA on a business trip with a colleague to, ironically enough, attend the National Emergency Number Association (NENA) 911 conference. The author had a fully functioning voice service for the duration of the trip from his service provider while his colleague did not have access to a voice or SMS service from a different service provider. This contrast of experience is something that will be the subject of much discourse in the coming weeks and months with many end-users scratching their heads trying to figure out the reason why.

The reason is quite simple. 2G and 3G mobile networks are being switched off and the 4G voice service, Voice over Long-Term Evolution (VoLTE), is implemented in different ways on different networks with variations between handsets, chipsets and software versions. Compatibility and interoperability issues between networks and handsets are starting to emerge which means that a voice service may not be guaranteed depending on the handset/network combination to roaming end-users. Other underlying causes may include:

  • Incorrect interpretation/implementation of technical standards for VoLTE;
  • Varying degrees of capability of chipsets installed in handsets;
  • Interoperability issues between networks and handsets for support of Internet Protocol versions 4 and 6 (IPv4/IPv6); and
  • Limited implementation of VoLTE roaming agreements between Mobile Network Operators (MNOs) internationally.

The purpose of this article is not to take a deep dive into the potential root causes of this issue. It is also not to point a finger of blame at any individual stakeholder or the industry as a whole. On the contrary, it is to understand how public safety risk is heightened by it, how that risk can be mitigated in the short term and eventually resolved.

This issue is not limited to visitors to the USA. In fact, visitors to any country that is leading the way in closing down 2G and 3G networks may experience this issue. VoLTE services have been available on some networks and devices for over 10 years[2] now but have run in parallel to legacy voice services provided over 2G and 3G networks. So even if you could not connect to a VoLTE service while roaming you could always rely on a good old fashioned legacy voice service. The reason for shutting down 2G and 3G services is to reallocate the radio frequencies designated for these services to new and innovative 4G, 5G and 6G (yes, 6G!) services which use the frequencies more efficiently to provide higher capacity services.

Not a problem in Europe ……yet

You may wonder why this issue is not being experienced in Europe by roaming end-users travelling across the continent. The answer to this is also quite simple. A number of critical services are still provided using 2G and 3G networks. For example, utility smart metering and eCall, the emergency call system mandated in all new type passenger vehicles since April 2018, rely on 2G and 3G networks. Resolving these legacy issues will take some time which means that 2G and 3G networks will prevail in Europe for some years to come.

In the short term, the substantive issue for roaming end-users of not having access to a voice service can be somewhat addressed by MNOs in Europe advising their customers of the associated risk and how to mitigate that risk. For example, those travelling to any country that is well advanced in switching off 2G/3G legacy services could be advised by their service provider to purchase a separate device and/or SIM card to ensure that they have access to a voice service. They could also be advised to manually select an alternative roaming partner that still offers a 2G/3G service (note: this option depends on the extent of the roaming agreements in place by the end-users home service provider and visited networks). This would be a positive step at this juncture because resolving the underlying technical issues may take some time and a shorter-term risk assessment and communications campaign is absolutely necessary in the interim.

Circuit-switched fallback reliance for emergency calling

While not having access to a voice service may be just an inconvenience for some, the risk of not having the capability to call emergency services is a grave concern. In Europe, the slower rate of 2G/3G shutdown could be a silver lining in a dark and menacing cloud of public safety risk. It means that all involved stakeholders have time to put their heads together and take corrective action before very serious public safety risk manifests itself.

VoLTE services are widely available in Europe but are not widely used for emergency communications. When a citizen makes a voice call to the pan-European emergency number, 112, the network will use available 2G/3G services to originate, transmit and terminate the call. This is referred to as circuit-switched fallback (CSFB). Some of the reasons for implementing CSFB include:

  • Availability of 2G/3G voice services on mobile networks offering very wide geographic as well as population coverage;
  • The robustness of a tried and tested solution for voice services; and
  • The possibility that some public networks, and the customer premises equipment installed in some public safety answering points (PSAPs), may still have active legacy components.

In 2021, the Dutch telecoms regulator, the Authority for Consumers and Markets (ACM), recognised the risk of continued reliance on legacy 2G/3G services for emergency communications which were approaching end-of-life. ACM urged service providers to become fully compliant, by the end of the year, with the national policy rule for emergency calls to 112 by providing access from 4G VoLTE and Wi-Fi calling services. Subsequent stakeholder discussions in the Netherlands led to the identification of the same compatibility and interoperability issues currently being experienced by European roamers in the USA. A warning sign if ever there was one!

Emergency calls only

2G/3G network specifications allow for a limited-service state (LSS) to be provided to a mobile device for the sole purpose of making an emergency call. When an end-user does not have access to their service provider’s network or the network of one of their roaming partners, an “emergency calls only” message appears at the top of their screen. When this happens, any available network can be used to make an emergency call. LSS also works in some countries when using a device which does not have a SIM card. This is an invaluable safety net for citizens and our PSAPs in Europe receive multiple LSS calls each and every day. As part of the analysis into the VoLTE compatibility/interoperability issue, stakeholders need to ensure that LSS emergency calling will continue to prevail after 2G/3G switch-off.

Where next for Europe on this issue?

In the short term, decisive and immediate action needs to be taken so that citizens are made aware that they may not be able to access emergency services in the USA, and potentially other countries, while roaming. In this respect, each and every mobile service provider should assess the potential risk for their own customers who may be planning to travel to any country in which they have roaming partners. This will require discussions with roaming partners and handset providers with whom they have commercial relationships. Based on this risk assessment, a communications campaign should be designed and implemented to inform customers of the risk and advise on steps that could be taken to mitigate this risk.

In the longer term, the compatibility/interoperability issues need to be resolved. This requires a more harmonised implementation of the VoLTE technical specifications that is compatible and interoperable between all networks and handsets. European policy makers, telecoms regulators, standardisation bodies, mobile network vendors/operators/service providers, handset and handset OS providers, industry representatives and consumer representatives will need to cooperate and collaborate to make this happen.

The European Telecommunications Standardization Institute (ETSI) recently issued a call for expertise[3] to extend the interoperability test specifications for VoLTE to include interworking test specifications for support of emergency services over VoLTE. The authors consider this a crucial step in resolving this issue and the call for expertise is open to ETSI members and non-members.

Reasonable expectations

As end-users of mobile services, we have been roaming seamlessly on mobile networks around the world for the best part of a quarter of a century now. It is reasonable for us to expect, and indeed we do take it for granted, that we will have access to a voice service to stay connected. It is also a reasonable expectation for us to be able to call for help if and when we need to. In the European Union, access to emergency services is a right of all citizens. That right is enshrined in legislation and those authorised to provide electronic communications networks and services are entrusted and required to ensure that access is constantly available to their customers. Access to emergency services can never be allowed to become an afterthought in the design of any future electronic communications networks and services. This current situation suggests it has become an afterthought. However, there is still time to put things right before any tragic incidents occur through the implementation of short-term mitigation measures and longer-term technical solutions. All stakeholders now need to put their heads together to protect our citizens.

The European Emergency Number Association (EENA) has been in contact with all of the main stakeholders to mobilise a collective effort to resolve these issues. EENA will also be writing to the European Commission, the Federal Communications Commission in the USA, industry and consumer representative bodies and national telecommunications regulatory authorities in Europe to raise awareness of the issue and to request them to play their part in resolving it.

Lives may depend on it.

Freddie McBride (EENA) and Rudolf van der Berg (Stratix Consulting)

This article was published in the Crisis Response Journal (September 2022 Issue).

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[2] MetroPCS lights up Voice over LTE (VoLTE) services, starts selling LG Connect 4G, August 2012