What’s the buzz about Push to Talk?

You may have come across the term "Push-to-Talk" while perusing your newly purchased cellphone’s owner’s manual and wondered what it was all about. Or you may have come from a trip overseas, particularly North America, and heard or even witnessed friends or acquaintances using this new communications technology.

So what exactly is Push to Talk? Often described as a "walkie-talkie" service using mobile phones, Push-to-Talk (PTT) is a service that makes one-on-one and group conversations possible over a cellular network. Press the button once and everyone can hear you talk, release the button and hear the others talking back to you.

The benefits of Push to Talk include direct speech connection that’s spontaneous and convenient; instant sharing of information and experiences, at any time; the ability to get and stay in touch with a group of people, whether they’re pre-set, impromptu, or open chat groups; and expanded range and roaming options over two-way radio.

Phones with the PTT feature have a dedicated PTT button that is used to start a session. A session can involve from two to several participants but only one person can talk at a time.

To start a Push-to-Talk conversation, you simply select a contact (in either phone num-ber or special PTT address for-mat) or a group from your list or the list of a friend. Then press and hold the PTT button or any button that’s assigned this function. When you hear a tone, you can start to talk. When you’re done, you release the button and wait for a response.

It sounds similar to walkie-talkies because it is. Both use "half-duplex mode," which means that only one person can talk at a time, and then only by pressing a button. The speaker is transmitting packets of data to the listeners, who cannot stream data while they are receiving it. The difference is that walkie-talkies operate over radio frequencies, while PTT conversations are sent over cellular networks, giving increased range and roaming capabilities.

Features of PTT that are not offered in two-way radio communication include auto-answer, where the caller is immediately connected to the recipient (as opposed to a phone call which the recipient must first answer before talking); invitation messages that work like voicemail alerts for users already involved in one PTT session to join another as soon as they are free; and conversation "managers" that determine who can talk at a certain time. Group calling can be conducted within set groups already established or created just before the session by sending invitations, or among individual PTT participants coming together in a "chat room" that can be either open or restricted.

It’s important to note that this definition deals specifically with Push to Talk over Cellular (also known as PoC), which operates over GPRS networks specifically. This means that you can start a conversation, chat with a friend for five minutes, then say nothing for 20 minutes, and then chat again for another five minutes without re-initiating the session. The "talk bursts" are delivered in packets rather than in a continuous stream like a regular telephone call.

PTT sessions over GPRS networks generally have faster session set-up times than PTT sessions over CSD networks, meaning they generally use radio resources more efficiently and therefore usually cost less. However, instant communications is never guaranteed and delays can occur depending on your operator agreement and that of your conversation partner anywhere from zero to six seconds.

In America, Push to Talk has been a function available from Nextel. That changed recently when Verizon Wireless announced the availability of the first phones with a PTT capability similar to that offered by Nextel.

The first phones to use the feature on the Verizon Wireless network are made by Motorola, which seems intent on using the PTT capability it has designed for many of its phones as a standard mobile phone feature. The network operated by Verizon Wireless uses CDMA (Code Division Multiple Access), which is the dominant type of wireless phone network in the United States. But the dominant type in the world is known as GSM/GPRS (Global System for Mobile Communications/General Packet Radio Service).

Motorola, Nokia, Ericsson and Siemens are developing PTT-capable phones for GSM/GPRS. And Samsung is said to have a CDMA phone with PTT on deck for the near future and one for GSM/GPRS soon after.

If it becomes as popular as the proponents hope it will, we have to wonder if Push to Talk will spur the invention of its own CB-like lingo. While business users are the primary targets, younger users will take to it in the same way they have with text messaging and phones with integrated cameras.

Perhaps, all that’s required for a nostalgic revival of the CB-trucker mania is a technology platform that makes it cool and marginally relevant. Will the Metro reverberate with the long-forgotten sign-off of the CB-era,"That’s a big 10-4, good buddy!"? Probably not. But in the wireless world, stranger things have happened.