Several technologies and networks have the capacity to enable mobile VoIP: 2.5G and 3G cellular as well as Wi-Fi and WiMAX networks. Voice can be managed either by the network itself, or by software solutions installed on the handset. Release 5 of UMTS will enable end-to-end IP management.

The market is getting off the ground with VoWi-Fi solutions: particularly through integrated cellular/Wi-Fi offers. Wide-scale deployment of these solutions is expected for 2006, but not until 2008 on cellular network.

The success of wireless VoIP will depend mainly on the rates charged for voice calls on 3G networks, on the availability of unlimited data packages, on the regulatory situation, and on the availability and price of the handsets themselves (Wi-Fi and dual mode cellular/Wi-Fi).

Two business models for wVoIP could emerge: the first, developing initially in the United States and whose driving force will be independent Wi-Fi access networks, and later mobile operators, will resemble the internet model.

The second model, which is likely to be the most common one in Europe and Japan in the coming years, involves wVoIP being "controlled" by mobile operators, and incorporated into their rate plans.

Driving technologies

By the end of 2004, VoIP over the fixed network had begun to be adopted in Asia, North America and Europe thanks to the growing use of broadband access and SIP. The outstanding question now is the possibility of carrying VoIP over to mobile networks. The stakes this represents for mobile operators are particularly high, given that 80% of their earnings are currently telephone based. To give body to VoIP's emergence on the mobile calling market, several technical options are possible.

On cellular networks, aside from increasing bit rates on the radio channel, it should be noted that, more and more, network standards include IP mode. Added to this, the handsets' increased memory enable the use of VoIP client software, plus a growing number of compatible operating systems are becoming available on mobile phones. UMTS TDD and CDMA 2000 EV-DO will make it possible for operators to deploy VoIP relatively quickly, but most of the players feel that, in the medium term, it will be evolved 3G architectures (UMTS release 5, with an IMS architecture--based on SIP--and CDMA 2000 EV-DO Rev. A) which will enable optimal convergence between a fixed and mobile network.

WLAN and BWA technologies have provided good conditions for Voice over IP processing since the 802.11e standard's release, and have proven more credible solutions than Bluetooth. As to WiMAX, the 802.16 norm enables voice transport, while version 802.16e will enable mobility management.

Software solutions like Skype, Wengo and MSN Messenger can be used on high quality 2.5G networks, using a compatible operating system running on the handset

Launch of commercial offers

Currently, most commercial deployments involve Wi-Fi solutions for integrated Wi-Fi-WiMAX/cellular services, thanks notably to the UMA protocol. The most advanced in this field are clearly Asian carriers Korea Telecom and Japan's DoCoMo. KT markets a service that lets users equipped with dual mode mobiles (WiBro/cellular) or PDAs switch over to Wi-Fi at hotspots. And the service is expected to become more widely available in the coming months thanks to WiMAX. For its part, DoCoMo offers a 3G/WiFi service which is geared chiefly to business users. Meanwhile, in the US, veteran operators are planning to launch this type of service by the end of 2006, in part to improve coverage (notably by investing in WiMAX networks) and in part to further their quad play bundling strategies. But it is especially the newcomers, like Vonage and Skype, who are shaking things up. Skype has signed an agreement with Motorola for its Skypein services to be available on the manufacturers' handsets, for use on either Wi-Fi or 3G networks. When equipped with a compatible OS, users can also use Skype software directly, although cellular operators are working to limit this scenario as much as possible. Vonage too offers VoWi-Fi services, thanks in part to its collaboration with manufacturer UTStarcom. Several of Europe's mobile operators are marketing GPRS/UMTS/WiFi services as well and most carriers who operate a UMTS licence have tested the TDD solution, but none have plans for wide-scale deployment before 2006/2007.

Benefits and obstacles for users

Studies have shown that in, Western Europe and in the US, over a third of all calls made on a mobile phone are placed either from the home or the workplace. This means that, potentially, over 40% of outgoing calls can be processed using a Wi-Fi device connected to a WLAN (home network or hotspot). These solutions allow users to enjoy lower calling rates, better coverage and greater quality of service (particularly in the United States). In countries where the recipient pays a portion of the cost of the call, this cost is eliminated, and the price of long distance calls is much lower than the price charged by a cellular network (close to 70% in the US). VoIP over Wi-Fi or software solutions reduce certain costs dramatically, including international and out roaming calls. It is chiefly business users who are involved here, and who are likely to benefit initially. The growing use of IP on cellular, WiFi and WiMAX networks enables not only voice calls over IP but several new services as well. Most notable among these new services are IM and presence (possibly combined with global positioning), videophony and video phone conferencing. And, in the business world, VoIP can be integrated into collaborative work software suites.

Dual mode terminals are still quite expensive, and UMTS TDD handsets will not be available until 2006. Wi-Fi devices still have fairly limited autonomy, but are improving gradually. Added to this, roaming between different operators' Wi-Fi networks still needs to be resolved. And, finally, there remain the classic issues of security and data encryption. These are particularly important issues for businesses which are already reluctant to deploy fixed network-based VoIP solutions.

What strategies for the players?

For mobile carriers who already operate a 2G network, the long-term goal is to build a single network capable of carrying both voice and data. For most operators, the migration to an IP transport network is already underway, and is likely to take another two or three years to complete. The migration to an all IP architecture takes between 5 and 8 years. The migration process will be both complex and costly for operators. The leading mobile carriers will no doubt enjoy a sizeable drop in their costs over time--hardware costs will drop and transport costs are negligible--but a TDM network will need to be maintained throughout the process, as will support for non-VoIP enabled handsets. Because of the huge rise in traffic per user and the competition between the top two 3G standards (UMTS and CDMA 2000 EV-DO), mobile operators in the US could be pioneers in the migration to all IP. Once TDM networks can be shut down, sizeable benefits will ensue, both in terms of the network's operation and the ability to develop new multimedia or rich voice services.

The emergence of MVNOs specialised in data could pose a threat to mobile carriers if these new players are able to buy data capacity wholesale at a low price, to then resell data services--including mobile VoIP--retail.

While awaiting the deployment of all IP architectures, mobile operators'strategies are being built around the following areas:

--new calling rates, with offers from integrated operators that combine fixed broadband and Wi-Fi, in a bid to cement the loyalty of high potential subscribers;

--increasing Wi-Fi hotspots in a bid to expand coverage and gain a larger share of the market;

--blocking the initiatives of VoIP software designers, either at the hardware or network level, or through actions at the regulatory level;

--VoIP offers on the cellular network, targeting heavy users (businesses especially), including unlimited flat rates for calls that are the least costly to the operator (on-net traffic, off-peak times of the day or week), plus the development of rich offers as part of voice/data packages (voice, SMS, MMS, e-mail, videophony, conference calls, ...).

Wireline carriers and WISPs, such as BT, can hope to capture a portion of mobile operators' revenues thanks to Wi-Fi and Bluetooth technologies, both in the home and at work. In particular, the possibility of becoming an MVNO allows wireline telcos to market bundled offers that include broadband access, fixed voice over Wi-Fi and mobile voice. Voice services can be accessed using dual mode handsets. This strategy can also be combined with Wi-Fi or WiMAX coverage in high-density areas, in a bid to capture a portion of outdoor traffic. In theory, these integrated (fixed and mobile) players are in a better position than solely mobile operators.

wVoIP provides an interesting opportunity for specialty service providers and software publishers as well. A great many players like Yahoo, MSN and AOL began by marketing mobile IM services, followed by fixed VoIP services and, more recently wVoIP. At the same time, VoIP software (Skype, Net2Phone ...) includes more and more features (presence, conferencing, videophony, etc.), and is working to become network agnostic. Progress is also expected to be made for the corporate segment (notably at the NAT and firewall levels). These players are lobbying to have regulations as open as possible, in a bid to force mobile operators to open up their networks. They are also forging alliances with hardware manufacturers, in a drive to equip the handsets with open OS and VoIP software in the factory. So network agnostic VoIP software represents major opportunities for fixed and mobile hardware producers.

VoIP growth scenarios up to 2010

By 2010 we are likely to see two growth scenarios for VoIP on mobile networks:

Swift emergence of VoIP on cellular and WiFi/WiMAX networks

This growth scenario is most likely in the United States where cellular coverage is mediocre. Use of Wi-Fi and dual mode cellular/Wi-Fi handsets will spread quickly, while smartphones equipped with operating platforms that are compatible with VoIP application downloads will become more and more popular. WISPs (Wireless Internet Service Providers), mostly spin-offs of mobile operators and cablecos, support this approach as part of their quadruple play offerings. Having to contend with the threat of a sizeable drop in traffic, mobile operators are forced to react by investing in WiMAX networks, while waiting for UMTS release 5 technologies to become available in 2008. Faced with this competition and with a drop in calling rates, they will need to develop richer and more personalised services.

Limited growth of VoIP on mobile networks

Under this scenario, which we feel applies best to the situation in Europe, cellular operators are working to limit VoIP's impact on the mobile network, in a bid to amortise their TDM networks and the cost of their 3G licences. Since most cellular operators are owned by wireline telcos, they will gradually merge their networks into a single convergent one. Cellular operators are testing UMTS TDD-based services for a selection of market segments (corporate and technophile consumers), revising their rate plans to better compete with ISPs and MVNOs, and seeking to block software solutions by gaining control over the handsets via subsidies, or by lobbying for regulations that forbid the use of VoIP software on mobile phones. This strategy could, however, be thwarted by regulators if they were to approve data MVNO agreements or rule that operators' initiatives were illegal. Under this scenario, a significant portion of the market could be captured by wireline telcos and MVNOs, particularly with their combined broadband/ Wi-Fi/cellular packages. Here, the "big leap" towards wVoIP is not expected to happen until 2010.

(*) This report, published by IDATE, provides a comprehensive analysis of wVoIP technological challenges, networks, handsets, software solutions, wVoIP commercial deployments, trials and growth scenarios for 2005-2010.

Frederic PUJOL

IDATE, Montpellier

Table 1 - Network technologies and availability for mobile VoIP

Network                Type of terminal                  Availability

Wi-Fi                  Wi-Fi only: PC cards, portable    2004-2005
                       or bi-mode (cellular & Wi-Fi)     2005
WiMAX (802.16e)        PC cards, portable                2007
Cellular EDGE or 3G    PC cards, portable,               2005
                       communicating PDA)

Source: IDATE

Table 2 - Wireless VoIP's potential and chief growth factors, by
geographical zone

                                         Western Europe

                                     Situation controlled by
                                     mobile operators in the
                                           short term.
                                    Limited potential for the
                                          next 5 years.

New entrants                                    +
WISPs controlled by cellular                    -
operators
Impact of MVNOs                                +++
Cable networks/possibility of                  ++
quad play bundles
State of development of mobile                 ++
data traffic
Level of cellular subscribers'                  +
voice traffic
ARPU level                                      -
Mobile networks' indoor coverage                +
Rate of cellular penetration                    -
Growth of the PDA/smartphone                    +
market

                                          North America

                                       Immediate potential
                                            on Wi-Fi
                                      Potential on cellular
                                       networks in 5 years

New entrants                                   ++
WISPs controlled by cellular                    +
operators
Impact of MVNOs                                ++
Cable networks/possibility of                  +++
quad play bundles
State of development of mobile                  +
data traffic
Level of cellular subscribers'                 +++
voice traffic
ARPU level                                      +
Mobile networks' indoor coverage               ++
Rate of cellular penetration                    +
Growth of the PDA/smartphone                   ++
market

                                              Japan
                                           South Korea

                                           Favourable
                                           environment
                                        Mobile operators
                                        promoting Wi-Fi /
                                      cellular integration

New entrants                                   ++
WISPs controlled by cellular                    -
operators
Impact of MVNOs                                 +
Cable networks/possibility of                   +
quad play bundles
State of development of mobile                 +++
data traffic
Level of cellular subscribers'                 ++
voice traffic
ARPU level                                     ++
Mobile networks' indoor coverage                -
Rate of cellular penetration                    -
Growth of the PDA/smartphone                   ++
market

Legend: "+++": Very positive; "-" : Negative