Business people use IP-based mobile calling today. What most are doing, however, is utilizing platforms and services aimed at consumers. Service providers and a wide array of vendors are increasingly looking at business travelers as a unique market group. "Right now, mobile VoIP continues to grow in popularity with businesses of all sizes," says Garrett Smith, the director of marketing and business development for VoIP Supply.

The confusion in the segment is caused by the many ways in which hardware and software vendors and service providers are approaching the sector. The target audience also is segmented: There are large enterprises, SMBs and SOHOs, all with different levels of sophistication and different ways in which they need their data and voice integrated. It is likely, however, that at least some of the confusion will be addressed in the next year as the plans and technology mature and the bad economy eliminates marginal players.

Lots of Action

A lot is happening, especially among European-based service providers with worldwide customer bases. "It has exploded the last month or so," says Tommy Jensen, the chairman of mobile VoIP service provider Vyke. "We have 40 of the Fortune 500 testing our solutions right now."

While mobile VoIP is increasingly becoming part of organizations' collaboration strategies, the initial attraction is what always intrigues people and companies: saving money. This is especially true during the recession and particularly resonates with businesses, who welcome any way to cut expenditures on international roaming and hotel phone charges. "Moving from GSM to VoIP on the mobile side offers really substantial savings, a 50 to 65 percent cost reduction," Jensen says.

These services can be offered in a number of ways. For instance, software clients can create an IP-based "softphone" within a phone or laptop. This functionality can be the product of partnerships between the service providers and the smartphone vendors or it can be generic software downloads usable on a wide variety of endpoint devices. Many involve hybrid approaches in which calls to local cell numbers are transported over wired IP networks and the Internet.

Effectively serving the business sector is far more than finding a way to get software into a phone or laptop or establishing jerry-rigged hybrid ways to connect calls. Smith says that consumer mobile VoIP companies are approaching business travelers directly or by partnering with carriers who have back offices, large established customer bases and, in some cases, actual networks.

At this point, the most serious carriers are second- and third-tier players, says Gizmo5 CEO Mike Robertson. "Those companies are open to mobile VoIP," he says. "They are not winning, not adding new customers. They have to compete with the bigger, better-funded companies."

Another approach focuses on creation of dual-mode phones able to deftly switch between the cellular and wireless networks. These phones are part of the larger drive, fixed mobile convergence (FMC), which seeks to merge wired, wireless IP and cellular networks in a way in which the strengths of each are leveraged.

From the Inside Looking Out

The software vendors and service providers are, in essence, looking in from the cloud. The view from the ground — the ground, in this case, being in the enterprise — is to extend the corporate PBX to the wireless and cellular world beyond the firewall. Indeed, Disruptive Technologies founder Dean Bubley suggests that the label "fixed mobile convergence," popular a few years ago, has given way to the sobriquet "mobile unified communications."

Extending the PBX — both the legacy and IP versions — is done either by the vendors themselves or in conjunction with "pure-play" fixed mobile convergence equipment makers. These firms, says Philippe Winthrop, an analyst with Strategy Analytics, include Agito, Tango, CounterPath, Canadian firm NewStep and DiVitas. Clearly, there are many players and many approaches. It will take time for all of this to sort itself out. "There is no answer to who is ahead," Winthrop says.

It is a difficult market to assess because there is so much innovation. For instance, Mobivox this year shifted its focus from going directly after consumers to partnerships with organizations that already have consumer relationships. Those end users — which could be business people, members of social networks, or even subscribers to legacy phone networks — access a hosted address book. They request their party through a voice-activated or text interface. In October, the firm announced that it is providing these services to UNYK, an online address book with more than 11 million users. Mobivox CEO Peter Diedrich says that the organizations with which the company will partner will serve both consumers and business users.

Skype is the top banana in VoIP with about 370 million registered users. Ian Robin, the director of Skype for Business, says that about one-third use the service in connection with their work. One-third of these are thought to be mobile.

The company's Skype for Business offers corporations a dashboard in which they can manage multiple Skype clients running on devices — both desktop and mobile — used by their employees. End-user features, however, are the same as the consumer version of Skype.

Increasingly, Robin says, the company is looking to integrate itself more deeply in enterprise networks. To do this, it has to link to the legacy PBX or IP PBX. Precisely how this will be done will differ on a case-by-case basis. Currently, Skype has an arrangement for such deals with open source IP PBX vendor Asterisk. Robin says more deals — with IP-PBX/PBX makers, service providers, handset companies and others — are expected in 2009.

Perhaps the best way to conceptualize this big, important and nebulous market is as one in which enterprises are trying to reach out to the nascent IP-based mobile telecommunications network and that network, in turn, is trying to reach in. The ecosystems that do the most successful reaching will make the most money. In the long run, the coming of 4G — Long Term Evolution (LTE) and WiMax — will simplify matters because it mandates an all-IP approach. The question, says Bubley, "is how we get from here to there."

VoIP Supply's Smith sees the lower costs as the most attractive element in the short term and advanced features becoming the driver once the financial picture brightens. "When you start to see cheap minutes integrated with existing business applications or software and the voice enabling of things, that's where it gets really powerful," he says.