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Challenges of VoLTE roaming, by Dhiraj Wazir, EE

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30 November 2016

Dhiraj Wazir

Blogs by author:  Dhiraj Wazir , Head of Interconnect & International Enablers, EE.

VoLTE is fast becoming a must for operators across the world. Dhiraj Wazir, Head of Interconnect and International Enablers, EE explains why this is the case, outlining the current VoLTE landscape and detailing the ongoing challenge facing the telecoms industry: VoLTE roaming.

Now being deployed by over 530 networks in 170 countries, 58% of the human race can enjoy the benefits of 4G/LTE. It’s only a natural evolution that VoLTE follows data on LTE. This in itself is a big challenge, but we’ve already got 86 networks in nearly 50 countries who have rolled this out, and the device manufacturers aren’t far behind with over 228 devices now capable of VoLTE calls.

This is proof (if one ever needed one) that operators across the world see the benefits of moving to an all IP world. The benefits are wide ranging, including cost efficiency, being able to run all services on a single network, and the possibility of spectrum re-farming. But it also provides the opportunity to roll-out rich services and to up the ante against OTT players.

VoLTE roaming

Telecoms isn’t a place for the faint-hearted, and VoLTE roaming continues to challenge network operators. It’s early days, but we’ve had 7 unilateral and 2 bilateral roaming VoLTE launches announced.

Roaming has been more challenging than expected as operators are taking their time to come to grips with the key question: S8HR (S8 Home Routing) or LBO (Local Break Out)?

LBO is clearly the “Engineers” choice: it’s clean, straight-forward, service aware at the VPMN and calls can be handed over to 2G/3G should a handset run out of 4G coverage while the user is mid-call. Unfortunately, as this requires IMS interworking and rigorous testing for each handset type, it seems impractical to deploy for each roaming partner.

All the launches announced so far have used S8HR primarily driven by speed to market, even though Lawful Intercept on S8HR is still being worked on by 3GPP, and SRVCC (Single Radio Voice Call Continuity) seems impossible on S8HR.

Roaming managers deploying S8HR also have to tackle the implication of service unawareness at VPMN. This means that the VPMN can only charge for a VoLTE call on a per MB basis and not per minute as is the case with traditional 2G/3G voice. This to a certain extent divorces retail charging from wholesale Inter-operator tariffs, as network operators will continue to charge the end customer per minute rather than as a data session.

The fact that a VoLTE call has a QCI with a Guaranteed Bit Rate, and the volume of data it generates will primarily depend on the codec used by the HPMN, makes life shall we say “very interesting” for roaming managers. Not only do they need to figure out how many Mega Bytes equal one minute, but this will be different for each codec.

To keep life simple operators may opt to start charging by APN rather than QCI, but this has the side effect of requiring the same charge for signalling as well. The question that remains to be answered (and only time will help solve) is whether roaming managers will monetise quality and opt for charging based on QCI, or will they opt for simplicity with a single charge.

Should we care to look to history for some guidance, we were here when 3G was launched and standards were created to differentially charge for GPRS and 3G data. But as far as I’m aware not a single operator adopted this, and data simply remained data.

S8HR does provide the HPMN with more flexibly as we are freed from the shackles of international IOT’s (Inter Operator Tariffs). All calls come home as a data packet, so the VPMN cannot have a differential charge based on the destination of the call, and the HPMN can choose its own carriers to forward route its calls to other destinations. This will not only be cheaper, but will give the HPMN control over what quality it wants to offer its customer.

The first battle has most certainly been won by S8HR … Will LBO come back and become the standard, or is this BETAMAX Vs VHS all over again? Watch this space – it’s about to get very interesting!

To discuss further with BT and EE team, you can write to us at lets.talk.gtm@t.com.

This article was first published in 5GWorldNews.com here.