Saturday, April 25, 2009

Fixed Mobile Convergence(s)

The term "fixed mobile convergence" is very ambiguous. In this post, I will try to clarify the concept by distinguishing between different types of convergence and by positioning IMS with regards to them.

Device convergence

This type of convergence essentially relies on the ability of a device to connect to a single or to separate networks using either fixed or mobile access (typically WiFi behind xDSL and GSM/UMTS).

UMA (Universal Mobile Access), also called Generic Access Network (GAN) in 3GPP, is a potential solution for this type of convergence, as it permits to add an IP access to the mobile core network while keeping the higher level signaling stacks, thus enabling standard handover between, e.g. WiFi and cellular access. UMA/GAN requires the support of a dedicated "base station" in the access network to add the new access to the mobile core.

The IMS Voice Call Continuity (VCC) specification supports a similar feature, but this time handover is performed through switching between an IMS core network and the mobile core network. An issue with VCC is that voice services are supported across two different core networks (IMS and the pre-IMS mobile core), which may cause trouble with regards to the execution of value added services that should be unified or at least coherent across the two networks. The 3GPP IMS Centralized Services (ICS) initiative could be a way to address this issue, by locating value added voice services for both IMS and the pre-IMS mobile core network in a single IMS Telephony Application Server (TAS)

Overall, device convergence suffers from the significant hurdle to rely on dual mode devices, with the need for associated market penetration. It may also face technical issues related for instance to the quality of user experience or battery consumption. Note that this is the only type of convergence which relies on the ability of a device to connect to the network through different access types.

Service convergence

Service convergence relies on the support of convergence through service implementation.

Typically, fixed and mobile devices each access their own network through their specific access. A service is then made convergent by an ad hoc implementation permitting the coherent delivery of the service across the different access technologies and devices. This generally implies federation between fixed and mobile identities, the usage of a converged service profile and a consolidation of fixed and mobile OSS/BSS functions in order to deliver a coherent provisioning and a converged bill.

The drawback with this approach is that services have to be made convergent one by one, either by totally service-specific implementations or by the integration with a usually proprietary convergence framework dealing for instance with identity federation and shared fix / mobile service profiles. This type of convergence may be costly to support, difficult to evolve, and may sometimes be limited due to technical issues.

Network convergence

Network convergence relies on the ability of a core network to support different types of devices using different access technologies.

A single IMS core network may for instance support a variety of access technologies among GSM, UMTS, LTE, Femtocells, WiFi, WiMax, xDSL, FTTH, circuit-switched fixed access and cable, and consequently the devices making use of them.

IMS based network convergence requires the ability of the device to connect with IMS, either through native or acquired internal support, through a home gateway or through a network gateway. On the other hand, it does not require the device to support various access technologies (like WiFi and GSM/UMTS).

Taken in isolation, network convergence is essentially a cost reduction feature as it permits to avoid deploying access-specific core networks, thus cutting in the CAPEX and OPEX of the operator. Fixed and mobile devices can still make use of different user identities associated to different service profiles, and providing access to discriminated services or service implementations.

However, network convergence can also be seen as a support facilitating the implementation of service convergence, as it implies the support of the same (IMS) protocols by the devices (or through gateways) as well as a unified access to application servers through the unique core network. IMS-based network convergence can therefore be used to support convergent services in a more cost effective and simplified manner.

Network convergence is currently a strong IMS driver for operators deploying new access technologies (e.g. WiMax, LTE) or targeting specific convergent services (e.g. enterprise FMC, converged messaging) across these new or legacy access technologies.

In addition, IMS-based network convergence can also be seen as a step towards the ultimate goal of user convergence.

User convergence

User convergence relies on the support of a unique converged subscription possibly making use of converged user identities (i.e. user identities shared between fixed and mobile devices). It builds and extends upon network convergence.

In this approach, the operator provisions a unique user profile in the HSS, which may include converged identities, separate fixed and mobile identities if needed, and access specific information like authentication methods and credentials (e.g. UMTS AKA for mobile and SIP digest for fixed).

In the most advanced scenario, the user can concurrently register the same user identity (e.g. from multiple fixed and mobile devices. The service profile stored in the HSS and associated to the shared identity supports converged access to IMS application servers, which associate a converged user profile to this identity. In this approach, every service deployed on the IMS framework and associated to a converged identity is de facto converged because immediately accessible from various devices using vaious accesses.

SIP requests addressed to the converged identity (e.g. incoming calls, incoming instant messages) can be handled intelligently by the IMS core network (and possibly the application layer) with a panel of strategies ranging from alerting the user or delivering the request (e.g. an IM) on several devices to selecting the most appropriate one according to various criteria such as user preferences, device capabilities and more dynamic information such as presence.

Other interesting features include session mobility (currently worked on in the IETF and 3GPP) permitting to transfer an ongoing session from one device to another, as well as the possibility to deliver the different components of a multimedia session over different devices (CPM requirement), like delivering the video component of a voice/video session to the TV and the voice one to the mobile phone.

I had the opportunity to describe user oriented convergence in a previous post, but I will use this one to demystify prejudices that sometimes exist about it.

First, while IMS can eventually support user convergence, it will not mandate it for all users. An operator implementing a coherent IMS strategy will be able to offer convergent subscriptions while keeping the possibility to offer mobile and fixed specific subscriptions as well (using IMS network convergence in this case). Moreover, even for converged subscriptions, the operator will be able to keep separate fixed and mobile identities if the user wishes it or for access to specific services. This is only a matter of user profile provisioning in network databases.

Second, user convergence does not necessarily mean the impossibility to distinguish between fixed and mobile access for:
- Service discrimination: some services may remain fixed or mobile specific.
- Service implementation discrimination: variants may still exist between the implementations of a service depending on the access used to deliver it.
- Charging discrimination: differentiated fixed and mobile charging may apply as long as users are informed about it, possibly in an interactive manner before service delivery.

The key element permitting to support these differentiations is the fact that all SIP signalling originating from a device includes an identification of the access technology it uses (e.g. UMTS, xDSL). This information can be used for service routing in the network (i.e. definition of initial filter criteria) or within service logic prior to or while delivering the service. A device switching from one access to another during service delivery would inform the network about it, for instance by initiating session re-negotiation, thus permitting the network and services to dynamically adapt to the change.

User convergence will not happen overnight, as it implies, besides the addressing of pending technical issues, major changes related to organizations, processes, business models, OSS and BSS, as well as regulation. However, I cannot imagine that it will never happen, whether this is under the control of operators using IMS or through disruptive players using alternative solutions enabled by all-IP networks.


IMS can support all types of convergence: device convergence, service convergence, network convergence, and user convergence.

Personally, I consider that device convergence and service convergence are of a limited and tactical appeal, due to the limitations and costs they imply. Moreover, to support them, IMS is only a candidate framework among others, which alone may not justify an investment.

The real interest of IMS for fixed mobile convergence appears when network and user convergence are part of the roadmap for the operator. These targets justify the usage of IMS for device and service convergence, as an initial step towards a more ambitious strategy combining both network and user convergence. Network convergence in itself can be used as an intermediate step towards user convergence, which will be a true revolutionary aspect of IMS, together with its ability to support multimedia communication, to combine services and to merge the Internet and telecommunications domains.

Saturday, April 11, 2009

Who reads The IMS Lantern?

As a complement to my latest post on IMS deployments, I think that an analysis of the audience of The IMS Lantern can provide interesting insights about the IMS community all over the world.

Since June 2007, this blog generated over 41,000 visits from 132 countries.

Worldwide audience

From a continental perspective, Europe accounts for half of the traffic and generated more than twice as many visits as the Americas and Asia, which are head to head.

However, the USA are, by a large margin, the country which tops the others in terms of traffic.

Here are the top 20 countries:
1. United States

2. France

3. India

4. Germany

5. United Kingdom

6. Sweden

7. Canada

8. Spain

9. South Korea

10. Switzerland

11. Italy

12. Netherlands

13. Japan

14. Slovenia

15. Israel

16. China

17. Singapore

18. Taiwan

19. Austria


Visits come from three main types of companies:

- Big network equipment vendors including those leading on the IMS market, but not only.
- Operators, mainly from the USA, Canada, France, Spain, Germany, South Korea, Japan and Australia.
- Application service suppliers, with a huge domination from India.

However, a significant part of the traffic is also generated by smaller vendors providing equipments, services or OSS/BSS systems, by suppliers of service platforms, and by research centers, engineering schools and universities.

Subjects of interest

Visitors are mainly interested in posts describing technical details about the IMS service architecture, IMS identities, the SCIM, and IMS data management. This may hint at a deficiency in the way the literature, courses and IMS specifications address these topics.

Just behind come posts dedicated to the innovative features of SIP and the IMS service architecture, like the User Oriented Architecture (UOA), fixed mobile convergence, multimedia SIP sessions and CPM, and the various service patterns I had the opportunity to describe. I am personally very happy to see that CPM, which is by far the most ambitious IMS standardization initiative, attracts a lot of curiosity and is often entered as a keyword in search engines. Moreover, the post dedicated to it is the one visitors spend the most time on. Another source of more personal satisfaction is to see that the concept of User Oriented Architecture that I associated to the IMS has started to spread outside of the blog, even if it is far from having reached mainstream acceptance yet.

The IMS Lantern therefore seems to be accessed as both an educational and thought-provoking resource on the IMS.

Sources of traffic

Visits mainly come from search engines with IMS-related queries and from people who regularly visit the blog or get notified about new posts.

A smaller portion of the traffic comes from links on other sites (mainly blogs addressing telecom or technological topics). I have done very little to advertise The IMS Lantern on the Internet, but do not hesitate to link to it if you have the opportunity to do so.


Does The IMS Lantern have an influence on the work of some people or companies in the industry?

I know from direct contacts and some references visible on the Internet that The IMS Lantern has influenced research activities, the writing of theses, articles and even a book that will be published in the coming months.

It is a great source of motivation for me to learn that others can benefit from what I am writing and I have no problem with the reuse of ideas and information I am providing through this blog. So don't be shy: if this blog has a direct or indirect influence on what you are doing, just let me know.

Wednesday, April 8, 2009

A List of IMS Deployments

While I was doing research for this post, I stumbled upon a March announcement which provides an ideal introduction to it.

Infonetics Research issued a 2008 4th quarter report claiming that:
- Worldwide sales of IMS equipment nearly doubled in 2008 over 2007, up 94%
- Unlike many other markets during the worldwide economic crisis, the IMS equipment market is expected to grow in 2009 and 2010
- Infonetics’ IMS Deployment Tracker shows Ericsson, Alcatel Lucent, Nokia Siemens (NSN), NEC, and Huawei leading the way with core IMS equipment

In this post, I am trying to list done or ongoing deployments of IMS core networks all over the world. This list is based on publicly available contracts announcements and, in case I was not able to find such material, public evidence or strong hints that such deployments were at least under way. When available, I mention the date of the contract, the supplier of the core network, and the intended focus of the deployment, at least in its initial phase. Otherwise, question marks replace the information.

My intention is to maintain this list over time, based on new annoucements as well as the additions or corrections you might be able to give to me by email (cgourraud at or by posting a comment. For instance, in many cases, a press release relates to a contract signed at a group level or for a specific country for service providers operating over several ones, and any precision on the actual country(ies) targeted for deployment would be useful.

I hope this list can be of interest to you. The idea came to me from recurent requests to provide information of IMS deployments in Europe, North America and Asia.


ArmenTel: 8/2008, Ericsson, Fixed Network -> FMC

Mobilkom: 1/2009, Nortel, Mobile network

Delta Telecom: 9/2008, Alcatel Lucent, WiMax network

Belgacom: 4/2008, Alcatel Lucent, Fixed network

Vivatel: 11/2008, NSN, Mobile network

CYTA: 12/2006, Ericsson, FMC

Czech Republic
Eurotel: 12/2005, NSN, Mobile network
Vodafone: 9/2007, Ericsson, Enterprise FMC

TDC: 6/2005, Ericsson, Enterprise

Elion: 9/2006, Ericsson, Fixed network

Bouygues Telecom: ?, ?, RCS
France Telecom/Orange: ?, ?, RCS
Hub Telecom: 11/2008, Alcatel Lucent, Enterprise FMC
SFR: ?, ?, RCS

Arcor: ?, ?, ?
Deutsche Telekom: ?, in-house solution?, ?
T-Mobile: ?, ?, RCS
Vodafone: 7/2007, Ericsson, Consumer & Enterprise

Hella Online: 1/2008, Ericsson, Fixed network

Tele Greenland: 1/2008, Ericsson, FMC

Magyar Telekom: 7/2006, Huawei, FMC
T-Mobile & T-Com: 7/2006, Huawei, Mobile network / FMC

O2 Ireland: 8/2006, Ericsson, Mobile network
Vodafone: 7/2008, Ericsson, Mobile network

Telecom Italia: 2/2005, Ericsson, Fixed network
Telecom Italia Mobile: 2005, Ericsson?, RCS
Wind Telecomunicazioni: ?, ?, RCS

KPN: 9/2006, Alcatel Lucent, Fixed PSTN replacement

Exatel: 10/2007, Alcatel Lucent, Fixed network
Netia: 9/2005, Alcatel Lucent, Fixed network / Enterprise services
Telekomunikacja Polska: 3/2007, Ericsson, FMC

Optimus: 3/2006, Ericsson, Mobile network
Portugal Telecom: ?, 2007?, FMC / PSTN replacement
Sonaecom: 7/2008, Ericsson, Fixed network/IPTV
TMN: 6/2005, NSN, RCS
Vodafone: 7/2007, Ericsson, FMC

Comstar: planned in 2009, to be selected, fixed network / PSTN replacement
Sibirtelecom: 6/2006, Nortel, ?

Telefonica: 4/2005, Ericsson, Fixed network
Telefonica/O2: ?, ?, RCS

Com Hem: 6/2007, NSN, Fixed network
Telenor: 7/2007, Ericsson, Enterprise FMC
TeliaSonera: 5/2007, NSN, FMC?

Swisscom: 2/2007, Ericsson, FMC

Turkcell: ?, ?, Mobile network / FMC

BT: 4/2005, Ericsson?, Fixed PSTN replacement

North America

Bell Canada: ?, ?, FMC
Rogers Cantel: ?, ?, ?

AT&T: 10/2005, Alcatel Lucent, Mobile network
Bellsouth - now AT&T (USA): 11/2005, Alcatel Lucent, Fixed network
Cox Communications: 2007?, ?, Cable network
Sprint Nextel: ?, ?, FMC
SureWest Communications: 4/2008, Alcatel Lucent, Fixed network
TerreStar Networks: 7/2007, Alcatel Lucent, Satellite and Cellular convergence
Time Warner Cable: 4/2009, NSN, Cable network
Verizon Communications: 3/2007 - 2/2008, Alcatel Lucent & NSN , Mobile network/PSTN network replacement/FMC

South America

Brasil Telecom: 5/2008, Ericsson, Mobile network

Asia & Oceania

Commander Communications: 9/2005, Ericsson, Fixed network
Telstra: ?, Alcatel Lucent?, ?

Beijing Netcom: 4/2007, Ericsson, Fixed network
China Mobile: ?, ?, RCS
China Netcom: ?, Alcatel Lucent?, ?
China Unicom: 7/2007, Alcatel Lucent, Mobile network
Fujian Telecom: 12/2006, NSN, FMC

Hong Kong
NWT: 7/2006, Alcatel Lucent, Fixed network
SmarTone-Vodafone: 4/2008, Ericsson, Mobile network

Telkomsel: 8/2006, NSN, Mobile network

KDDI: 1/2006, NEC, RCS
NTT: ?, ?, ?
Softbank Mobile: 12/2006, Ericsson, Mobile network
Softbank Mobile: 9/2008, NEC, Femtocells network

Celcom: 7/2006, NSN, Mobile network

Globe Telecom: 9/2006, NSN, FMC

South Korea
KTF: ?, ?, RCS
SK Telecom: 2005 or 2006, ?, FMC/RCS

Chungwa Telecom: 12/2007, NSN, Fixed network
FarEasTone: 9/2006, Ericsson, Mobile network

Saigon Postel Telecommunication: 11/2006, Ericsson, Fixed network

Middle East & Africa

Mena Telecom: 8/2007, Motorola, WiMax network

Wateen Telecom: 5/2006, Motorola, Fixed network

South Africa
Telkom: 2008?, ?, ?

Warid Group: 10/2007, Huawei, Mobile/WiMax network