The cellular companies are getting hungry for enterprise customers. After years of focusing on the consumer markets and the individual mobile professionals that comprise the ranks of the country's Fortune 500, carriers are ready to go after the Fortune 500 themselves.

But in targeting those companies, carriers are finding the vast cellular footprints they've built for the mass markets aren't exactly tailored to the needs of the enterprise. The voice-centric, public networks that so handily drove consumer penetration to record levels don't exactly fit the data-centric, private model that enterprises are looking for in their networks.

“As wireless networks have evolved, carriers have always tried to focus on the enterprise but they haven't had the relative tools, aside from voice, to be relevant to business,” said Chris Ebert, Nokia's executive director of convergence and service enablement platforms.

But with the networks now data-capable and quickly upgrading to broadband-capable, the cellular operators are now sitting on assets that potentially could be very attractive to business.

“If the question is ‘is the network good enough?’ then the answer is ‘yes,’” said Pankaj Asundi, chief technology officer for Ericsson's enterprise group in North America. “The core infrastructure is in place. The real question is ‘where do you optimize?’”

One of the primary ways to optimize those networks is through tweaking the infrastructure from core to radio access network. Wherever there is new infrastructure to deploy there are vendors who will sell it, and they each have a different philosophy about what makes a network more enterprise friendly. For Cisco Systems, it means making the public network look more private.

“Carriers are running very public networks,” said Larry Lang, vice president and general manager of Cisco's mobile wireless group. “They can't make those networks completely private, but there are ways they can make them virtually private.”

Cisco's contribution to the field is its home agent and service selection gateways, which, according to Lang, allow businesses to recreate their corporate LANs on the carrier's network — or at least make it look like they are. Both products are built from the mobile IP specification, a wireless offshoot of standard IP, allowing users, nodes and data to move from the enterprise network to the cellular network without interrupting IP sessions or transferring to an entirely new addressing scheme.

The gateway is an authentication and authorization server allowing subscribers various levels of access to the Internet, but it also allows carriers to create a private walled garden of content for individual enterprises — basically a semi-private network on the public network. While enterprises control the levels of authorization and the content their mobile workers access, the carriers are still managing the overall customer experience, intervening whenever there is a problem.

Cisco's home agent, deployed at the operator's data center, provides the intelligence to negotiate the prickly handoffs between networks. Like other vendors' home agents, Cisco's box digs into packets, dictating quality of service (QOS) and the priority of packets. But Lang said Cisco's home agent also allows for virtual routing of an enterprise's private IP addresses, basically allowing businesses to treat phones and laptops on the cellular network as terminals hooked to the office LAN.

“The key here is that the mobile network is just one of the many networks an enterprise will use,” Lang said. “Carriers have to not only create a semi-private network for these enterprise customers, they have to promote their ability to fit in with all kinds of other networks.”

While Cisco focuses on the IP core, other vendors are developing products for the radio access network. Since the Cellular Telecommunications & Internet Association's Wireless 2005 show, Nokia has been promoting its new Internet-High Speed Packet Access (I-HSPA) technology, which targets enterprise and other heavy data users over the wireless wide area network (WAN). Built as a data-only complement to its high speed downlink and uplink packet access (HSDPA and HSUPA) UMTS technologies, an I-HSPA radio carrier sends a data stream directly from the base station to the IP network gateway, bypassing the radio networking controller and signaling network.

The purpose of the technology is to give carriers a more efficient data channel, allowing them to pare the costs they charge to high-volume data users, Nokia's Ebert said.

“From an enterprise perspective, it's a very cost-efficient solution,” he said. “It provides a dedicated broadband wireless network that mirrors the cellular network.”

Perhaps the most significant issue facing carriers and their networks isn't one quantifiable in terms of equipment or applications. It's one that's quantifiable in terms of QOS and network availability — benchmarks that reflect the status of the network as whole, instead of a particular element. And the only way to tackle those issues is by improving network capacity, adding cell sites and adding channels at existing cell sites.

Eugene Signorini, Yankee Group director of wireless strategies, said there is evidence that carriers are willing to expand their networks on a case-by-case basis to attract a specific business customer. He pointed to a recent win by Cingular Wireless where in order to secure a contract with the state of Tennessee, the carrier deployed new in-building EDGE and GSM cell sites in the state capitol, other state office buildings and underground parking facilities.

“Cingular deployed infrastructure in areas where it would only be used by state employees,” Signorini said. “It's showing it's willing to go the extra mile to win a customer.”

Although deploying semi-private infrastructure to boost capacity within a customer's building seems to be a growing trend, the fate of the overall WAN is another story. Most enterprises need their connectivity and reliability outside of the corporate office where mobile workers depend on the wireless network to link them back to the office. While carriers have made great strides in improving overall network quality during the last five years, it still may not be at the level enterprises expect.

The enterprise community has always relied on service level agreements (SLAs) from the wireline providers to ensure their business-critical applications and communications get the network quality and capacity they need. So far, however, the wireless industry has done little to add those SLAs to its enterprise offerings. In fact, most of the growth in the wireless space has been driven by new customers adds — market share was the metric of success. But there are shifts detectable among the carriers as they take the reliability concerns of enterprises more seriously.

Sprint is now the only carrier to offer SLAs for both its wireless data and voice services. But a study of Sprint's voice SLA conducted by the Robert Francis Group found that the service guarantees Sprint offers aren't exactly stellar. Sprint's voice SLA has three components: blocked calls, calls dropped and general network availability. If the total number of blocked or dropped calls exceed 2% of total calls on the network or if the overall network availability falls below 99.9%, the customer is eligible for a service credit.

Though 99.9% reliability falls short of the SLAs that wireline carriers traditionally offer (many wireline carriers are now offering 99.999% availability SLAs for their IP networks), three nines is a pretty hefty guarantee for a cellular network. But RFG points out that the SLA for network availability as well as dropped and blocked calls is calculated on a nationwide basis. When there is a network failure, it usually impacts a specific market or region, and the likelihood that the entire national network would fall below 99.9% availability is highly unlikely, RFG said. So even if a major problem were to knock half of Manhattan off of the network during business hours for half a day, the effect on the overall network would not be enough to trigger the SLA's service credits.

“Unlike the wired world of data communications, enterprise clients do not have network management tools available that can help validate whether or not Sprint's performance metrics were actually achieved,” the RFG report concluded. “This is somewhat analogous to the old saying of ‘hiring a fox to guard the chickens’ or perhaps the more commonly used adage ‘trust me.’”

Still, RFG and several other analyst groups give Sprint credit for at least instituting an SLA of any sort, instead of merely presenting a ‘best-effort’ service to its perspective enterprise customers. Sprint's SLA, even with its limitations, will most likely become the benchmark for other carriers as it introduces its own SLAs and the starting point for improved guarantees as carriers make the SLA ammunition in their competition to attract business customers.

There's no doubt that carriers will aggressively court enterprises in the coming years. With voice revenues falling and their future staked in data services, operators are counting on the data dependencies of the country's business community to be a prime consumer of their 3G wares.

The top three carriers in recent months have all launched new enterprise initiatives, from Verizon Wireless' new push e-mail application to Sprint's new location-based services open platform. What's more, new IP multimedia subsystem overlays are expected to drive that service deployment at even faster rates as carriers' networks' become open standards-based IP architectures. Analysts like Yankee Group's Signorini expect that operators will begin layering on more and more functionality in their networks that they won't merely present to enterprises as services packages, but rather as elements over which enterprises can build their own applications.

Meanwhile, RFG believes carriers will gradually build more reliability into their networks and stop shrinking away from the SLAs that enterprises are demanding. In a few years, carriers will start offering more robust guarantees to lure in enterprise customers, regardless of whether their networks are truly ready to support them. Sooner or later the right combination of network quality, coverage and applications will come together that will trigger the enterprise's acceptance of cellular as a business tool.

“Our networks have undergone a lot of evolution, all of which is targeted at the enterprise,” said Barry Tishgart, senior director of wireless product management for Sprint's enterprise group. “We're using more open standards. We're providing portals into the enterprise LAN. We're erasing the difference between wireline and wireless.”