NEW YORK (CNN/Money) - It's a tough time for wireless carriers.

The one company that has enjoyed major success this year is Nextel, and most analysts attribute the company's good fortune to the fact that its walkie-talkie phones differentiate it from the rest of the industry.

With Fastchat, users scroll through buddy lists and can push a button to instantly connect to that person.

Nextel has the highest average revenue per user in the wireless industry and the lowest churn. In plain English that means Nextel subscribers pay more than anyone else a month and very few are finding a reason to cancel their plans. That's truly astonishing in an industry with brutal price competition.

One problem with Nextel, though: you can only talk to other people with Nextel phones. Have a Nextel walkie-talkie and you want to instantly get a hold of your brother on his Sprint PCS phone? No can do. (Of course, you could just give him a regular call).

But a small upstart company called Fastmobile has a push-to-talk product already on the market. The closely held company offers a service called Fastchat that can be downloaded from the Internet, just like a ring tone, to your phone. With Fastchat, just like Nextel, users can push a button to talk to other people who have the software on their cell phone.

Currently, Fastchat works on phones operating on the global standard for mobile communications, or GSM, which means that if you're a Cingular customer, you could talk to people who have service from AT&T Wireless or T-Mobile.

But Harry Eschel, co-founder of Fastmobile, said the company hopes to have a version that can be downloaded to phones that work on the competing CDMA standard within the next few months. Once that happens, Fastchat would be compatible with Verizon Wireless and Sprint PCS as well.

"Nextel deserves credit for converging the two-way radio with a phone. We wanted to take that feature and offer flexibility and freedom to contact people on different networks," Eschel said.

It all sounds cool but does the service work? I tested it out with two Nokia 3650 phones. So far, the only phones capable of downloading Fastchat are the Nokia 3650 and the Sony Ericsson P-800. But Eschel said more models from Nokia, in addition to some from Motorola, Samsung and Siemens, should be ready for the software by the end of the year.

I tried out Fastchat with my fiancée in our apartment and the service was a bit clunky. We were able to "talk" but often we did not get through to each other instantly. What frequently happened was that one of us would talk and then a second or so later, the other received a Fastchat voice message that you needed to play back.

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Playing around with the phones for a bit, the service started to work a bit better and we were able to engage in chats with Eschel and a public relations official for the firm in Chicago with very little delay.

All in all, I thought it was neat but ultimately, I'm not sure it's something I need, especially since the service was far from perfect. If I want to call someone on my cell, I can just do that. Waiting a few seconds for a connection is not that much of a burden.

If more people feel the way I do, that could ultimately be a problem.

Randy Rissman, former CEO of toy maker Tiger Electronics and now managing director of Leo Capital Holdings, a venture capital firm that has invested in Fastmobile, said the Fastchat service would be marketed more toward the average consumer rather than the blue-collar corporate market, such as the construction and transportation industries, where Nextel is dominant.

Another possible stumbling block is that Fastchat, which costs $9.95 a month for unlimited push-to-talk, text and picture messaging, is a voice over Internet protocol (VOIP)-based service, not a two-way radio connection like Nextel. So if you want to subscribe to Fastchat, your phone also needs to have a separate wireless Internet connection, which of course, costs more.

And when push (pardon the pun) comes to shove, it seems that the walkie-talkie aspect, and not Internet data services, is what is really driving demand for Nextel's service, according to industry analyst Greg Gorbatenko, at Loop Capital Markets. That doesn't seem to be lost on Nextel's competition.

Verizon Wireless is set to unveil its own walkie-talkie phones soon and Sprint PCS and AT&T Wireless are said to be looking at introducing their own products next year.

"Carriers got deceived into thinking that the true killer app was data but they are waking up to the fact that they need to be in push-to-talk," Gorbatenko said. "I'm a little concerned that Fastmobile may be too late to the party."

Eschel said that Fastmobile has so far raised about $5.2 million, which is not a huge amount, especially when you consider how much money the big cell phone carriers have at their disposal.

And so far, the company has only a few hundred paying customers. Eschel said Fastmobile hopes to have a more aggressive marketing push in the fall. For now the service is available at the company's Web site.