It was 2003 when cellular operators attempted to break the juggernaut that was Nextel Communications’ wildly successful walkie-talkie service with push-to-talk offerings of their own. Since then, the cellular technology has evolved significantly with aggressive price points and complementary mobile broadband services. This has paved the way for the possibility that fleet operators someday will abandon dedicated push-to-talk systems in favor of commercial cellular systems, particularly as the technology continues to evolve.

It probably won’t help the cause of dedicated push-to-talk players that Sprint Nextel’s iDEN nationwide service is fading. The company’s network modernization project, dubbed “Network Vision,” includes phasing out its iDEN network beginning in 2013 and deploying new multimode base stations. The operator’s plans call for the migration of iDEN customers to its CDMA platform that will feature new push-to-talk services beginning in 2011. However, it’s unclear what new push-to-talk services will run over Sprint Nextel’s CDMA network, given the fact that in 2009 it stopped offering CDMA push-to-talk devices based on Qualcomm’s Q-Chat technology and instead said it was focusing on enhancing iDEN again. The carrier hasn’t said whether Q-Chat will be brought back into the market.

Today, the two largest operators in the U.S., Verizon Wireless and AT&T Mobility, offer nationwide push-to-talk capability and compete with several regional operators, such as MetroPCS. And they have come to market with more bells and whistles than traditional two-way radios, such as mobile broadband services, a wider selection of handsets, better coverage and features such as instant voice messaging.

“The only advantage iDEN has over our cellular solution is call set-up,” said Bruce Lawler, chief marketing officer with Kodiak Networks, whose push-to-talk solution powers services from AT&T, several regional carriers including MetroPCS, and international operators such as France’s Orange and Telefonica throughout Latin America. MetroPCS is using a Kodiak platform that can initiate calls to any device, essentially setting up a bridge between the P2T network and the standard voice network.

SIDEBAR: The history of cellular push-to-talk solutions

Kodiak’s technology, which is integrated in several brands of mobile phones, uses a cellular network’s circuit-switched architecture to deliver push-to-talk services. Meanwhile, Verizon Wireless uses VoIP technology from Motorola to deliver push-to-talk services over its CDMA 1x EV-DO network.

Lawler said that cellular networks vary when it comes to how fast a push-to-talk call can be initiated. Typically over a CDMA network, calls take approximately three seconds to set up, and GSM can take even longer as the voice circuit searches for the devices to wake them up. In contrast, push-to-talk systems like iDEN-based networks average about 750 milliseconds for call set-up time.

“We allow the user to speak immediately, but the recipient doesn’t receive the call immediately,” Lawler said. The delay also exists on Verizon Wireless’ network, industry experts say.

For certain groups of users, that call delay does not matter because it is outweighed by the advantages they perceive in terms of cost, coverage and handset selection. For others, the delay is unnerving, said Rodney Johnson, vice president of sales and distribution with SouthernLINC, which provides iDEN service in major metro and rural markets in Alabama, Georgia, southeast Mississippi and northwest Florida.

“One of the major complaints we hear is that the latency and call set-up time are slower, and then there’s an unnerving double chirp,” Johnson said. “With iDEN, you push the big button, hear the infamous iDEN chirp, release the button and there is silence, and that person talks back to me. With push-to-talk cellular, the phone chirps both times, when you have a channel grant and when you release it. Customers find it hard to carry on a conversation.”

Along with the latency and longer call-set up times associated with cellular push-to-talk, Johnson that said a hardened infrastructure is also a key differentiator for the company. Its infrastructure is perhaps more hardened and reliable than Sprint Nextel’s thanks to the requirement that the network meet the needs of Southern Company’s local power companies during disasters and severe weather.

“When we see a customer go to push-to-talk on cellular, it’s typically based on price,” Johnson said. “There are some customers who don’t value the features of our infrastructure.”

SIDEBAR: Enterprises should look at commercial P2T, consultant says

SouthernLinc is also confident that once Sprint Nextel fades out its iDEN network that the technology will live on.

“We work a lot with Motorola and the International iDEN Operators Forum,” said SouthernLINC CEO Bob Dawson. “The technology continues to be enhanced, system releases are continuing to go into the network and handsets keep coming out. … iDEN being turned off by Sprint wouldn’t be a great day, but the technology will still go on. People who value push-to-talk will continue to be customers here.”

And SouthernLinc isn’t stranded with archaic handsets, Johnson contended. The company offers the iDEN BlackBerry 8350 device, and last May, it introduced Motorola’s i1 push-to-talk Android smartphone based on iDEN. The device offers a touch-screen phone that includes Web browsing and access to thousands of applications via the Android Market. While both smartphones are relegated to iDEN’s narrowband data service, which is ideal for short, bursty communications such as e-mail and messaging, users can connect to Wi-Fi hotspots for more data-intensive functions, Johnson said. In addition, the company’s GPS-based fleet management solution enables real-time tracking and location.

Dawson said that SouthernLINC’s customer base consists nearly equally of public-safety users, enterprise customers and consumer users. The operator offers a prepaid, push-to-talk plan that has been attractive to both consumers and businesses that are using it to curb costs in a tight economy.

SouthernLinc doesn’t recommend that end users take these devices as their primary push-to-talk phones if mission-critical communications is paramount. The company found that out the hard way when a tornado hit Prattville, Ala., on Feb. 18, 2008. “Smartphones and push-to-talk don’t work well in a disaster,” Johnson said. “We had deployed a lot of BlackBerrys to senior decision-makers. With all of the data, the push-to-talk traffic didn’t get to where it needed to go. … For mission-critical push-to-talk you need a dedicated device. … It could be an issue for cellular operators.”

Wireless consultant Andy Seybold concurs. During the International Wireless Communications Exposition (IWCE) in Las Vegas last month, Seybold said that commercial P2T services could be an attractive option for many enterprises, and added that it even could have a place in the public-safety sector for use by non-sworn personnel — but not for first responders.

“This is not designed to replace mission-critical voice for first responders,” he said.

Nevertheless, push-to-talk over cellular technology is evolving and continues to improve. At press time, Kodiak was poised to introduce the next generation of its push-to-talk cellular solution that uses a data connection over 1x EV-DO, HSPA, WiMAX and LTE networks, and closes the gap regarding call set-up times to the degree that it now is comparable to iDEN, Lawler said. He said that a major North American operator is on the cusp of introducing the solution this year.

Perhaps just as important is the fact that the solution can be used on most major smartphones without the requirement that it be integrated at the manufacturing level. End users will be able to download the client via mobile platforms such as Google’s Android.

Phil Redman, vice president with Gartner Group, said quality of service (QoS) parameters in data networks are now improving, which will make push-to-talk over cellular better in terms of call set-up times.

Early iterations of push-to-talk over cellular running over packet networks could not compete with LMR and iDEN networks because of the lack of QoS to prioritize the voice call in real time. Newer networks now support QoS and larger reverse links.

“VoIP translates into faster call set-up, greater diversity of handsets and the ability to bundle more service together over an IP channel than just voice,” Lawler said. “You can push data, voice messages, text messages, video and pictures over the same data connection.”

Redman believes that the advent of push-to-talk over IP will make the feature another smartphone application.

“The service will be menu-driven and IP-based, and every phone will have some sort of push-to-talk application,” he said.

With reporting by Glenn Bischoff.

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