'Push to talk' services picking up penny-wise phone users

By PETER GRIFFIN

It harks back to the days when two-way radio was all the rage, but "push to talk" services are gaining appeal among mobile operators taking advantage of better network economics to deliver cheaper calls.

Mobile equipment maker Ericsson and Vodafone are testing Ericsson's "Instant Talk" service locally that effectively brings instant messaging to the voice world.

The Americans have been doing it for years, using their mobile handsets as walkie-talkies, holding one-way conversations with friends wielding the same type of phone.

A small software upgrade can convert your existing mobile phone into a radio handset on which you can instantly start conversations with other mobile users without dialling a phone call.

Push to talk (PTT) is not a full duplex service, meaning only one person in the conversation can talk at one time. But therein lies its advantage.

PTT uses less network capacity as only one channel is open to those communicating. Mobile operators, therefore, are able to deliver a one-way voice service for a much lower cost than the two-way mobile calls we are used to making.

Although United States mobile operator Nextel has led the way in the development of push to talk, boasting some 11 million users, it has been slow to catch on outside the US.

Technically, PTT is not difficult to set up.

It can be delivered over a packet data network such as Vodafone's GPRS network or Telecom's cdma1X network.

The voice is delivered as packets of data and routed to its destination according to the users programmed in the software on the handset.

A flashing icon on the handset informs you that a caller wishes to speak to you. Pressing a button acknowledges you are free to talk, then you can press the button again to send your reply.

Said Jeremy Hope, Ericsson's market development manager: "Your PTT message then hits an application server and your voice message is then sent over [internet protocol] to the persons or group you have selected to deliver it to."

He said the service had huge potential for the consumer mass market.