Showing posts with label Roaming. Show all posts
Showing posts with label Roaming. Show all posts

Sunday, 1 November 2015

Quick Summary of LTE Voice Summit 2015 (#LTEVoice)

Last year's summary of the LTE voice summit was very much appreciated so I have created one this year too.

The status of VoLTE can be very well summarised as can be seen in the image above.
‘VoLTE network deployment is the one of the most difficult project ever, the implementation complexity and workload is unparalleled in history’ - China Mobile group vice-president Mr.Liu Aili
Surprisingly, not many presentations were shared so I have gone back to the tweets and the pictures I took to compile this report. You may want to download the PDF from slideshare to be able to see the links. Hope you find it useful.

Related links:

Saturday, 10 October 2015

VoLTE Roaming: LBO, S8HR or HBO

There was an interesting discussion on different roaming scenarios in the LTE Voice Summit on 29th, 30th Sep. in London. The above picture provides a brief summary of these well known options. I have blogged about LBO/RAVEL here and S8HR here. A presentation by NTT Docomo in a GSMA webinar here provides more details on these architectures (slide 29 onwards - though it is more biased towards S8HR).

Ajay Joseph, CTO, iBasis gave an interesting presentation that highlighted the problems present in both these approaches.

In case of LBO, the biggest issue is that the home operator need to do a testing with each roaming partner to make sure VoLTE roaming works smoothly. This will be time consuming and expensive.

In case of S8HR, he provided a very good example. Imagine a VoLTE subscriber from USA is visiting Singapore. He now needs to make a phone call to someone in Indonesia (which is just next to Singapore). The flow of data would be all the way from Singapore to USA to Indonesia and back. This can introduce delays and impact QoE. The obvious advantage of S8HR is that since the call setup and media go to Home PMN (Public Mobile Network), no additional testing with the Visited PMN is required. The testing time is small and rollouts are quicker.

iBasis are proposing a solution called Hub Breakout (HBO) which would offer the best of LBO and S8HR. Each VoLTE operator would need to test their interoperability only with iBasis. Emergency calls and lawful intercept that does not work with S8HR would work with the HBO solution.

While I agree that this is a good solution, I am sure that many operators would not use this solution and there may be other solutions proposed in due course as well. Reminds me of this XKCD cartoon:

Anyway, here is the iBasis presentation:

Sunday, 12 July 2015

S8HR: Standardization of New VoLTE Roaming Architecture

VoLTE is a very popular topic on this blog. A basic VoLTE document from Anritsu has over 40K views and my summary from last years LTE Voice summit has over 30K views. I assume this is not just due to the complexity of this feature.

When I attended the LTE Voice summit last year, of the many solutions being proposed for roaming, 'Roaming Architecture for Voice over LTE with Local Breakout (RAVEL)' was being touted as the preferred solution, even though many vendors had reservations.

Since then, GSMA has endorsed a new VoLTE roaming architecture, S8HR, as a candidate for VoLTE roaming. Unlike previous architectures, S8HR does not require the deployment of an IMS platform in VPLMN. This is advantageous because it shortens time-to-market and provides services universally without having to depend on the capability of VPLMN.

Telecom Italia has a nice quick summary, reproduced below:

S8HR simplicity, however, is not only its strength but also its weakness, as it is the source of some serious technical issues that will have to be solved. The analysis of these issues is on the Rel13 3GPP agenda for the next months, but may overflow to Rel14. Let’s see what these issues are, more in detail:

Regulatory requirements - S8HR roaming architecture needs to meet all the current regulatory requirements applicable to voice roaming, specifically:
  • Support of emergency calls - The issues in this context are several. For example, authenticated emergency calls rely on the existence if an IMS NNI between VPLMN and HPLMN (which S8HR does not provide); conversely, the unauthenticated emergency calls, although technically feasible in S8HR, are allowed only in some Countries subject to the local regulation of VPLMN. Also, for a non-UE-detectable IMS Emergency call, the P-CSCF in the HPLMN needs to be capable of deciding the subsequent action (e.g. translate the dialed number and progress the call or reject it with the indication to set up an emergency call instead), taking the VPLMN ID into account. A configuration of local emergency numbers per Mobile Country Code on P-CSCF may thus be needed.
  • ­Support of Lawful Interception (LI) & data retention for inbound roamers in VPLMN -  S8HR offers no solution to the case where interception is required in the VPLMN for inbound roamers. 3GPP is required to define a solution that fulfill such vital regulatory requirement, as done today in circuit switched networks. Of course VPLMN and HPLMN can agree in their bilateral roaming agreement to disable confidentiality protection to support inbound roamer LI but is this practice really viable from a regulatory point of view?
Voice call continuity – The issue is that when the inbound roamers lose the LTE coverage to enter into  a 2G/3G CS area, the Single Radio Voice Call Continuity (SRVCC) should be performed involving the HPLMN in a totally different way than current specification (i.e. without any IMS NNI being deployed).
Coexistence of LBO and S8HR roaming architectures will have to be studied since an operator may need to support both LBO and S8HR VoLTE roaming architecture options for roaming with different operators, on the basis of bilateral agreement and depending on the capability.
Other issues relate to the capability of the home based S-CSCF and TAS (Telephony Application Server) to be made aware about the VPLMN identity for charging purposes and to enable the TAS to subsequently perform communication barring supplementary services. Also, where the roaming user calls a geo-local number (e.g. short code, or premium numbers), the IMS entities in HPLMN must do number resolution to correctly route the call.
From preliminary discussions held at Working Group level in SA2 (architecture) and SA3 (security) in April, it was felt useful to create a new 3GPP Technical Report to perform comprehensive technical analysis on the subject. Thus it is expected that the discussions will continue in the next months until the end of 2015 and will overheat Release 13 agenda due to their commercial and “political” nature. Stay tuned to monitor the progress of the subject or contact the authors for further information!
NTT Docomo also did some trials back in February and got some brilliant results:

In the trials, DOCOMO and KT achieved the world's first high-definition voice and video call with full end-to-end quality of service. Also, DOCOMO and Verizon achieved the world's first transoceanic high-definition VoLTE roaming calls. DOCOMO has existing commercial 3G and 4G roaming relations with Verizon Wireless and KT.
The calls were made on an IP eXchange (IPX) and network equipment to replicate commercial networks. With only two months of preparation, which also proved the technology's feasibility of speedy commercialization, the quality of VoLTE roaming calls using S8HR architecture over both short and long distances was proven to be better than that of existing 3G voice roaming services.

In fact, NTT Docomo has already said based on the survery from GSMA's Network 2020 programme that 80% of the network operators want this to be supported by the standards and 46% of the operators already have a plan to support this.

The architecture has the following technical characteristics:
(1) Bearers for IMS services are established on the S8 reference point, just as LTE data roaming.
(2) All IMS nodes are located at Home Public Land Mobile Network (HPLMN), and all signaling and media traffic for the VoLTE roaming service go through HPLMN.
(3) IMS transactions are performed directly between the terminal and P-CSCF at HPLMN. Accordingly, Visited Public Land Mobile Network (VPLMN) and interconnect networks (IPX/GRX) are not service-aware at the IMS level. The services can only be differentiated by APN or QoS levels.

These three technical features make it possible to provide all IMS services by HPLMN only and to minimize functional addition to VPLMN. As a result, S8HR shortens the time-to-market for VoLTE roaming services.

Figure 2 shows the attach procedure for S8HR VoLTE roaming. From Steps 1 to 3, there is no significant difference from the LTE data roaming attach procedure. In Step 4, HSS sends an update location answer message to MME. In order for the MME to select the PGW in HPLMN (Step 5), the MME must set the information element VPLMN Dynamic Address “Allowed,” which is included in the subscribed data, to “Not Allowed.” In Step 6, the bearer for SIP signaling is created between SGW and PGW with QCI=5. MME sends an attach accept message to the terminal with an IMS Voice over PS Session Support Indication information element, which indicates that VoLTE is supported. The information element is set on the basis of the MME’s internal configuration specifying whether there is a VoLTE roaming agreement to use S8HR. If no agreement exists between two PLMNs, the information element will not be set.

The complete article from the NTT Docomo technical journal is embedded

Monday, 29 December 2014

The SS7 flaws that allows hackers to snoop on your calls and SMS

By now I am aware that most people have heard of the flaws in SS7 networks that allow hackers to snoop, re-route calls and read text messages. For anyone who is not aware of these things, can read some excellent news articles here:

Our trusted security expert, Ravi Borgaonkar, informs us that all these flaws have already been discussed back in May, as part of Positive Hack Days (PHDays).

The presentation is embedded below and can be downloaded from Slideshare:

xoxoxo Added this new information on the 4th Jan 2015 oxoxox

The following is this presentation and video by Tobias Engel from the 31st Chaos Communication Congress

Wednesday, 25 June 2014

Diamater: Market Status, Roaming, NFV and Case Studies

Some more interesting presentations from the Signalling Focus Day of LTE World Summit. Good overview of market by Greg Collins of Exact ventures is embedded below.

A good presentation by Tieto where they presented some good case studies for Diameter Interworking. Presentation embedded below:

The final presentation by Diametriq is very interesting because they presented interesting way of mining the control plane. Thee case study presented was of a 'silent roamer' who is not going to spend money while roaming because he is not sure how much money is spent. This can be exploited by the operator to offer flat packages, 1 day pass, etc. to get some revenue from these roamers. Their presentation included some animations that cannot be shown while being embedded. Please download the PPT from Slideshare to view them.

Monday, 23 June 2014

LTE Roaming using IPX

A very interesting presentation from Raphaël Glatt of Bics in the Signalling Focus Day of LTE World Summit 2014. IPX is probably the most popular solution as its already being used by many operators for roaming agreements. Anyway, his presentation was the most detailed one I have come across and he was happy to share it with me for this blog. His complete presentation is embedded below:

Monday, 9 June 2014

European Regulations for 'Decoupling of SIM' and 'International Roaming'

The following is an extract from an article from Capana:

From the 1st of July 2014, the new EU Roaming Regulations III will become active.

The new EU Roaming regulations set by the European Commission, will allow retail mobile customers to purchase roaming services (such as voice, SMS and data) from an Alternative Roaming Provider (ARP) separate from their domestic service provider (DSP), without affecting either mobile number or device.
The general idea behind the regulations is to promote the interests of European citizens by increase competition between European operators, provide greater transparency, reduce bill shocks, and ultimately provide a greater roaming experience and higher quality of service for consumers.
European Commission President Jose Manuel Barosso said in a press release:
“Further substantial progress towards a European single market for telecoms is essential for Europe’s strategic interests and economic progress. For the telecoms sector itself and for citizens who are frustrated that they do not have full and fair access to internet and mobile services.”
Vice President Neelie Kroes, the Digital Agenda Commissioner responsible for package then continued in the same press release by saying:
“The legislation proposed today is great news for the future of mobile and internet in Europe. The European Commission says no to roaming premiums, yes to net neutrality, yes to investment, yes to new jobs. Fixing the telecoms sector is no longer about this one sector but about supporting the sustainable development of all sectors.”
The process of selecting an ARP and its services while abroad within EU is more commonly known as decoupling or separate sale of roaming services. BEREC (the body of European Regulators for Electronic Communications) have provided the European Commission with their recommendations of two decoupling models that should be supported; Local breakout (LBO, which is the local provisioning of data services by a visited network operator, or Single IMSI solution where the ARP acts as a reseller of the DSPs service offerings.
Decoupling using Single IMSI
With the Single IMSI solution the ARP will engage in agreements with each domestic operator providing domestic services, then the ARP will act as a reseller of these services to the roaming subscriber. This type of solution is applicable for all types of service providers such as mobile network operators, MVNOs or VSPs. From a subscriber standpoint, they will have a roaming agreement with the ARP regardless of the DSP and the DSP is required to activate services within one working day.
Decoupling using Local Breakout
The Local breakout model refers to local provisioning of data services only, where the services is provided directly on the visited network and traditional SMS and voice traffic is supplied by the home operator in traditional roaming manner. By using the 3GPP option for local breakouts, the VPMN will be able to act as ARP for internet access and other data services.
With these new regulatory changes, there is a higher demand on flexibility in billing systems. Support for more complex multi-partner business models for ARP and MVNO is necessary for both billing and financial settlement activities.

Raymond Bouwman from Rabion Consultancy did an excellent presentation last year in the LTE World Summit, here is his presentation explaining more about the EU Roaming Regulations III

Friday, 18 April 2014

International LTE Data and VoLTE Roaming - NTT Docomo

Quick recap of the Bearer Architecture: Remember the interface between S-GW and P-GW is known as S5/S8. S5 in case the S-GW and P-GW are part of the same network (non-roaming case) and S8 in case where P-GW belongs to another network than S-GW (roaming case). The S5/S8 interfaces are generally exactly the same. There is a possibility of different types of S5/S8 interfaces like GTP based and PMIP based but lets not discuss that here.

NTT Docomo published an excellent article in their magazine recently showing the different approaches to International Data roaming.

The different scenarios above are based on the guidelines provided in GSMA PRD IR.88. Each operator has to adopt one of the scenarios above, NTT Docomo has selected scenario 4. The Home PLMN (HPLMN) and the Visited PLMN (VPLMN) connect via IP eXchange (IPX).

As can be seen above, the MME in VPLMN communicates with HSS in HPLMN using Diameter Edge Agent (DEA).

Finally, it is well known that NTT Docomo is not launching VoLTE untill 2015. The above is their proposal on how they handle VoLTE while in Japan and when roaming.

The paper is an interesting read, embedded below:

Another article worth a read is the VoLTE roaming with RAVEL here.

Thursday, 13 February 2014

VoLTE Roaming with RAVEL (Roaming Architecture for Voice over IMS with Local Breakout)

Voice over LTE or VoLTE has many problems to solve. One of the issues that did not have a clear solution initially was Roaming. iBasis has a whitepaper on this topic here, from which the above picture is taken. The following is what is said above:

The routing of international calls has always been a problem for mobile operators. All too often the answer—particularly in the case of ‘tromboning’ calls all the way back to the home network—has been inelegant and costly. LTE data sessions can be broken out locally, negating the need for convoluted routing solutions. But in a VoIMS environment all of the intelligence that decides how to route the call resides in the home network, meaning that the call still has to be routed back.

The industry’s solution to this issue is Roaming Architecture for Voice over LTE with Local Breakout (RAVEL). Currently in the midst of standardisation at 3GPP, RAVEL is intended to enable the home network to decide, where appropriate, for the VoIMS call to be broken out locally. 

Three quarters of respondents to the survey said they support an industry-wide move to RAVEL for VoLTE roaming. This is emphatic in its enthusiasm but 25 per cent remains a significant share of respondents still to be convinced. Just over half of respondents said they plan to support VoIMS for LTE roaming using the RAVEL architecture, while 12.3 per cent said they would support it, but not using RAVEL.

Until RAVEL is available, 27.4 per cent of respondents said they plan to use home-routing for all VoLTE traffic, while just under one fifth said they would use a non-standard VoLTE roaming solution.

Well, the solution was standardised in 3GPP Release-11. NTT Docomo has an excellent whitepaper (embedded below) explaining the issue and the proposed solution.

In 3GPP Release 11, the VoLTE roaming and interconnection architecture was standardized in cooperation with the GSMA Association. The new architecture is able to implement voice call charging in the same way as circuit-switched voice roaming and interconnection models by routing both C-Plane messages and voice data on the same path. This was not possible with the earlier VoLTE roaming and interconnection architecture.

Anyway, here is the complete whitepaper

Tuesday, 29 October 2013

ANDSF: Evolution and Roaming with Hotspot 2.0

Access Network Discovery and Selection Function (ANDSF) is still evolving and with the introduction of Hotspot 2.0 (HS 2), there is a good possibility to provide seamless roaming from Cellular to Wi-Fi, Wi-Fi to Wi-Fi and Wi-Fi to Cellular.

There is a good paper (not very recent) by Alcatel-Lucent and BT that explains these roaming scenarios and other ANDSF policies related information very well. Its embedded below:

Friday, 31 May 2013

Friday rant: OTT, Viber, Roaming, etc.

The same old story, mobile operators are seeing that their revenue is not growing, even though they are upgrading their networks and introducing new features / technologies. The following is from Total Telecom:

The global telecom services market generated revenue of €1.12 trillion in 2012, although at 2.7% growth was slower than in the previous year, according to the 2013 DigiWorld Yearbook published by IDATE on Thursday.
The "DigiWorld" as a whole - which also includes telecoms hardware, software and computer services, computer hardware, TV services, consumer electronics and Internet services – recorded revenues of €3.17 trillion last year, up 2.8% on 2011. By 2016 that figure will have risen to €3.66 trillion, IDATE predicts, with telecoms services contributing €1.25 trillion (see chart).
Telecoms operators are experiencing flat growth, while over-the-top (OTT) providers are seeing revenues increase by 15% a year, Vincent Bonneau, head of IDATE's Internet business unit, told attendees at the DigiWorld Yearbook launch in London earlier this month.

Another interesting piece of news was that Viber has launched a desktop application which means it can now rival Skype fully.

Guess what, I would think that operators have more to worry from this news than Skype. I have stopped using Skype for some time now due to many issues I have with it and have moved to Viber for a few months.   If you are a regular reader to this blog then you would have read my recent post complaining about the global roaming rates. When I am travelling abroad, I make sure there is WiFi and use Viber as a substitute for Voice and SMS. In fact I can send MMS and emoticons using Viber which would cost a fortune over cellular otherwise.

Sometimes it feels like the operators are sleepwalking into their own destruction by not innovating enough and fast to be a challenge for these OTT services. Not entirely sure what the solutions are but there are quite a few ideas around to start thinking in that direction. An interesting presentation by Dean Bubley I posted here is a good starting point. Another one from him and Martin Geddes is embedded below, which is quite interesting and intutive.

Enough of my rants, what do you think about this?

Sunday, 19 May 2013

Is the Global Mobile Roaming model broken?

Yesterday, I noticed some heavyweights discussing roaming prices on Twitter. It is embedded below using the new Twitter embed feature:

Those who follow me on Twitter may have noticed me ranting about the roaming prices recently so I thought that this is a perfect opportunity to put my thoughts down.

As being discussed above, I went on the websites of two UK operators and found out about their roaming rates to India and The USA and they are as follows:

 It should be noted that there is a better rate available with some kind of bundle opt-in from both the operators and I have not shown about the other UK operators but they offer a similar sort of rate so I am not trying to single out O2 and/or Vodafone.

Since LTE is 'All-IP' network my interest is more from Data point of view rather than the voice point of view. A colleague who went to India recently decided that enough is enough and he bought a SIM in India locally. Apparently is just a bit too difficult to get SIM in India if you are not an Indian resident, nevertheless he somehow managed it. The rates as shown below was INR 24 for 100 MB of data.

Rs. 24 is something like $0.50 or £0.35. You see my problem regarding the data rates? People may be quick to point out here that India has the cheapest data rates in the world. On the other hand we look at US, the rates are as follows:

Even if we assume $15 / 1GB data, its far cheaper than the roaming rate which may be something like,  £3/MB = £3000/GB or £6/MB = £6000/GB.

I blogged about all the interesting developments that have been happening in LTE World Summit regarding the roaming solutions but what is the point of having all these solutions if the operators cant work out a way to reduce these costs. Or is it that they do not want to reduce these costs as they are a good source of income?

The operators complain that the OTT services are taking business away from them and turning them into dumb data pipes but to a lot of extent its their fault. People like me who travel often dont want to spend loads of cash on data and have worked out a way around it. Most of the places I visit have WiFi, most of my work is not urgent enough and I can wait till I am in a WiFi coverage area. In some parts of the world, still I have to buy an expensive WiFi access but compared to the roaming rates, its still cheap so I have stopped complaining about it. My decision to book a hotel depends of reviews, free breakfast and free WiFi. Some of our clients who give us their phone to use abroad strictly inform us that data should not be turned on unless its a matter of life and death.

If the operators dont change their strategies and work out a better solution for the roaming rates I am afraid that their short term gains will only lead to long term pains.

Do you have an opinion? I am interested in hearing.

Friday, 1 June 2012

On LTE Roaming ...

The IP eXchange (IPX) is used for data when the users roam between different networks. GPRS Roaming eXchange (GRX) is a service within IPX. One of the main areas of discussion within the LTE World Summit 2012 in the Signalling Focus day was roaming on LTE. Different vendors have different proposals and solutions; couple of them are as follows:

Interesting to see that iBasis has proposed LTE Signalling eXchange (LSX) as a way forward.

A presentation from Acme Packet (for an earlier conference) has interesting VoLTE roaming options proposal.

Finally, while everyone was focussing on LTE-LTE roaming, only Diametriq was looking at LTE-LTE/3G/2G Roaming. The relevant part of their presentation is embedded below.
Happy to hear more on this topic if anyone else wants to contribute. Please feel free to add comments.

Monday, 20 June 2011

Roaming with the IP eXchange (IPX)

From Wikipedia:

Traditionally, voice traffic interconnection between different operators has utilized the international SS7/TDM networks. However, lately the all-IP paradigm with VoIP is being rapidly introduced by different operators in various forms, such as IMS. In order to minimize the number of conversions between packet-switched voice and circuit-switched voice there is a clear need to deploy an IP based NNI (Network-to-Network Interface) and therefore an IP based interconnection network.

It is also evident that a large number of IP based services (such as Presence or IM) simply cannot be interconnected using a SS7/TDM network, further increasing the need for evolution into an IP based interconnection network.

Since the year 2000 GSM operators have been using GRX (GPRS Roaming Exchange) network for routing the IP based commercial roaming traffic between visited and home operators. Mainly 2.5G and 3G data roaming has been using GRX. GRX is a private IP network (separated from internet) consisting of multiple different GRX carriers that are connected to each other via peering points. However, GRX is limited only to GSM operator community and not all GRX's are capable of meeting the demands of real-time services.

Even though the GRX environment is not entirely suitable as a common IP network for interconnection and roaming, it offers a good starting point for the development of IPX. IPX development has been done in various GSM Association projects and working groups since 2004.

The following presentation is from LTE World Summit:

Friday, 12 June 2009

GPRS Roaming eXchange (GRX) for LTE/EPS Networks

The GSM Association (GSMA) has came to the realization that GPRS roaming based on bilateral relationships between individual GPRS operators is incredibly complex and expensive to maintain, in particular if the number of roaming partners is high. In fact, each operator will have to have N(N - 1) dedicated links to other operators (given that N is the global numbers of operators for which roaming should be supported). The GSMA has therefore recommended the use of a GPRS Roaming eXchange (GRX) for the Inter-PLMN GPRS roaming scenario.

The GRX is built on a private or public IP backbone and transports GPRS roaming traffic via the GTP between the visited and the home PLMN (Figure above). A GRX service provider has a network consisting of a set of routers and the links connecting to the GPRS networks. Moreover, the GRX network will have links connecting to other GRX nodes to support GRX peering between networks.

The GRX service provider acts as a hub, therefore allowing a GPRS operator to interconnect with each roaming partner without the need for any dedicated connections. This allows faster implementation of new roaming relations, faster time to market for new operators, and better scalability since an operator can start with low-capacity connections to the GRX and upgrade them depending on the bandwidth and quality requirements of the traffic. Other benefits of GRX are as follows:

Support of QoS: This aspect that will be very important for the GPRS services and, in particular, for the transition to 3G systems.

Security: The interconnection between the home operator and the visited operator uses the private GRX networks, hence does not require the overhead of maintaining expensive IPSEC tunnels over the public Internet.

DNS support: Through GRX it is possible to support a worldwide ".gprs" DNS root, where the various GRX operators will collaborate in managing the root and each operator's DNS servers will be connected to such roots to provide translation of DNS names specific to one operator.

In conclusion, GRX is introduced for GPRS roaming to facilitate the network operators for the interconnection between networks to support roaming and will play a very important role for the transition to third-generation systems.

In the LTE World Summit, Alex Sinclair, Chief Technology Officer, GSMA mentioned about the important role GRX will play in the LTE networks. The figure below are his views on GRX.

Diagram and Initial text Reference: IP in Wireless Networks By Basavaraj Patil, et al.

More information on GRX is available in GSM Association IR.34 document.