On Dec. 9 and 10, Syniverse hosted its first webinars on one of the next frontiers of LTE – Voice over LTE, or VoLTE. The sessions, titled “Lessons Learned: Implementing VoLTE Roaming,” included me along with our special guest, Keith Dyer, Founder and Editor of The Mobile Network. We were delighted to draw a larger number of attendees than anticipated, and to receive a lot of follow-up questions.
In this post, I select a few questions that I think are of the most interest and answer them in the brief video below, and also share the remainder of the questions and answers we received further below. In addition to this information, if you weren’t able to attend the webinars or would like to reference any parts of them, I invite you to listen to a webinar recording and check out the slides we used.
We hope you find this discussion about VoLTE interesting, and we look forward to building on it with more VoLTE webinars in 2016. If you have any suggestions for VoLTE topics, please share them in the comments section below.
Other Questions on VoLTE Following the Webinar
Today, which one is the most used model for VoLTE roaming, S8 home-routed or local breakout? What are operators doing to overcome the challenges for each model?
The most used and deployed model is the S8 home-routed model. Operators are using circuit-switched fallback (CSFB) for emergency calling. With regard to lawful intercept requests under this model, the serving network may not have the data requested from law enforcement. The serve network should consult its own legal counsel to ensure compliance with lawful intercept legal requirements.
The roaming model is changing in Europe because of regulatory changes. Do you think that affects VoLTE roaming migration?
Interesting question. It could, although as far as we know, no operators have said anything about this. The S8 home-routed model will follow the data regulation, and the local breakout model will follow the voice regulation. With the current voice codecs, and the current maximum wholesale and retail charges, the S8 home-routed model will be a lot less expensive than local breakout per minute voice call. EU operators with a lot of inbound EU roaming would get much more revenue from local breakout and 3G than they would from an S8 home-routed model.
Charging for VoLTE is a challenge. Has any operator implemented VoLTE charging through Syniverse? I thought these would be bill-and-pay, except for those using deep packet inspection for video.
The operators that have already implemented VOLTE roaming are basing their wholesale rates on data – not minutes. Retail charging can still be based on minutes of use since the call is routed through the home operator’s IMS core.
Facetime is available and ends up within the pure data settlement within the realm of roaming, so video on IMS may or may not be competitive enough. But would it definitely be more reliable within a carrier’s control?
Over-the-top telephony services, such as Apple’s Facetime, will not take advantage of LTE’s quality of service, so an operator’s implementation of IMS-based video calling can provide better quality. Wholesale charging for IMS video calling will probably be based on data usage – just as Facetime is.
Will there still be a requirement for near-real-time roaming data exchange (NRTRDE) for VoLTE ?
No, there will be no requirement. VoLTE local breakout will not even be supported by NRTRDE as all of the information to combat fraud is already available in the home network in real time. If operators are exchanging data records in NRTRDE (optional today), then S8 home-routed records would also be exchanged, but this is entirely optional and only exchanged when agreed upon between the roaming partners.
With the S8 home-routed model preferred by five to one, how is the Enhanced 911 issue accepted? Has the FCC weighed in on this issue?
We can’t comment on the FCC, but so far the conventional wisdom presented by the GSMA REVOLVER group is to simply fall back to 3G for emergency calling. Obviously, this isn’t foolproof as not all areas have 3G coverage and some operators are LTE-only. The 3GPP has been tasked with filling in the holes for the S8 home-routed model.
What about Latin America. When will be the timeline to implement VoLTE roaming?
Typically, VoLTE roaming is started after home launch of the service, and most Latin American operators have not yet offered the service. However, we know that some Latin American operators are showing interest in VoLTE trials, so we expect to hear more from this region in 2016.
What percent of bandwidth increase is typically seen with a new VoLTE network release?
This all depends on the bit rate of the codec, busy-hour calculations, MOUs per month, etc. Just as an example, for AMR WB at 12.65 kbps, a VoLTE call would take around 44 kbps with overhead. This equates to 22 concurrent calls per 1 Mbps (assuming 100 percent utilization). So if you did 1 million three-minute calls per month (or 3 million MOUs), you would have 161 concurrent calls, or utilize 7.33 Mbps of bandwidth at 100 percent utilization.
How successful do you think VoLTE domestic services are today? Do customers really appreciate the difference, in regard to net promoter score, average revenue per user, etc.? Or is the key driver still the benefits gained from a technical point of view?
The key drivers are operational efficiencies related to migrating customers to an all-IP network both on a technical level and a financial level. With that being said, being a consumer with a VoLTE device, I am pleasantly surprised with the call quality and the ability to place a video call without needing an over-the-top (OTT) application.
Isn’t lawful intercept an inbound requirement?
Some countries are making inbound lawful intercept a requirement, and those operators are reviewing their options. In other regions, operators are stating that if they don’t have the records to provide, they can’t be held accountable. Others are exploring the ability to retrieve records from the serving gateway.
What kind of new IMS services do you see?
Some services we see include enhanced messaging and IMS-based file transfer (RCS), support for multiple devices, integration with Web browsers (WebRTC), and IMS-based communications and controls for machine-to-machine (IoT) systems.
We heard from a carrier at the last LTE summit in Amsterdam that VoLTE is the answer against the over-the-top (OTT) threat. Do you agree with that? How can VoLTE help to reduce the losses caused by voice OTT apps?
With devices that are VoLTE-enabled, the client is embedded within the handset, which improves battery life. VoLTE also gives operators greater control on resource allocation. Knowing how to provide guaranteed network resources for IMS APNs and being able to selectively provide those resources provides a value proposition to the operator to provide a high quality of service for VoLTE and Video over LTE (ViLTE) calls to potentially monetize services for the mobile subscriber.
If we ignore free Wi-Fi for a moment, the OTT apps need data transport. VoLTE will roughly use the same amount of data as the OTT apps, whereas 3G calls are more expensive. Thus, subject to operators taking advice to ensure compliance with any applicable local open Internet, net neutrality, or antitrust and competition requirements, this can allow mobile network operators to compete on an equal basis with OTT companies.
LTE data roaming is currently using a regular GRX path. How the right quality of service for voice on an S8 home-routed scenario be guaranteed?
Many if not all Syniverse customers have migrated from GRX-centric commercial agreements to IPX agreements, allowing the commercial path to place quality of service as necessary on the IPX network. This allows an easy transition from a GRX connection to an IPX connection by adding class of service to the IP access links and ports.
Does Syniverse have voice specialists?
Syniverse has employed voice engineers for a number of years supporting multiple products, including the support of a wholesale VoIP network inherited from the Aicent acquisition.
How is testing set up between operators when preparing to launch VoLTE roaming?
Typically, operators agree to trial and provide the test plan to Syniverse for lab setup. Operators also complete trial agreements with Syniverse before the commencement of testing.
Is RCS starting to re-emerge as VoLTE gains traction?
There are possibilities. However, operators have still opted to put RCS on the back burner as they continue to invest in LTE and VoLTE.
Would you consider hosting IMS services as some of your IPX competitors are?
Syniverse is developing a hosted IMS service for a number of segment vertical markets.