02 April 2005

Push to Talk explained

* Emirates Team New Zealand tested Vodafone’s Push To Talk service

What is Push To Talk?
At the push of a button on a Push To Talk (PTT) capable phone, the mobile becomes a walkie-talkie, allowing users to talk to other users in their group who are logged in, without having to make a phone call.

So what does this mean, really?
Imagine a multi-storied building site and a site manager wants to know who is using the nail gun. Instead of making lots of calls to the construction crew’s mobiles, they instead pick up a PTT enabled mobile, push the transmit button, and ask the entire crew with a single transmission. All the crew who are logged into the group hear the question, and the nail gun is quickly located – saving time and money.

What networks are offering PTT?
Both Vodafone and Telecom have now launched PTT services. Telecom has trademarked its service P2T, while Vodafone is calling its service Push To Talk. Telecom’s operates on its 027 network, while Vodafone’s operates on its 2.5G GSM network.

If I buy the PTT service from Vodafone or Telecom, can they enable my existing mobile phone?

No... and yes. Right now you will need a mobile with PTT functionality built-in. Currently there are only three phones in the country that are PTT enabled. They are the Sanyo 4920 and Sanyo 7400, both on the Telecom network, and the Motorola V303P on the Vodafone network. However, Vodafone has also launched a downloadable application that can be installed on Symbian operating system GSM phones like the Sony Ericsson P910i, and the Siemens SX1 that will PTT enable the phone. This does not necessarily mean, however, that a standard phone, PTT enabled, will be a good PTT phone. Why? Because PTT phones must have very loud speakers to be effective, and having a dedicated PTT button factory fitted is also ergonomically better.

I have heard that the Nokia 5140 and the Siemens CX70 are both PTT phones. Why can’t I use their PTT functionality?
Both those phones operate on the Vodafone network. While it is likely that Vodafone will enable new phones as the year progresses, currently only the Motorola V303P can use its PTT functionality, because the Vodafone PTT infrastructure is built on Motorola components. Telecom say there is interoperability between all Telecom P2T capable handsets on its network – but at the moment that is only the Sanyo 4920 and Sanyo 7400

Do group members have to be close to each other to use PTT?
No. PTT uses the mobile phone network, so anywhere you have coverage you can PTT group members – from one end of the country to the other. Vodafone also notes that you can PTT internationally on its network, from any of the 29 countries where it has GPRS roaming agreements in place.

So is a PTT phone really a walkie-talkie
Not really. Walkie-talkies generate powerful radio signals to transmit to each other, and have a much higher SAR rating than a mobile phone (SAR is the standard used to measure the amount of radio wave energy absorbed by the body when using a mobile device). A PTT phone has no ability to operate outside the coverage area of a standard mobile phone, and like a standard mobile, only needs to generate a radio signal powerful enough to reach the nearest cell site.

What will it cost?
Although different rates will apply to different levels of users, Vodafone has launched a flat rate deal of $19.95 per month. The company says it has tested PTT with numerous companies, and found the average number of ‘pushes’ used per month was 250. A push is a single button click and transmission. Telecom is offering 300 PTT minutes free for two months, to users on a monthly plan who purchase a Sanyo 7400 phone (currently retailing at $599). Otherwise Telecom will charge $10 a month for 300 PTT minutes.

So I need a PTT account as well as my normal voice account?
Yes.

Where could our company save money with this service?
Vodafone says one of its main target groups for PTT is businesses that are already using radio telephones. It says these companies are typically spending around $75 a month per user on this equipment – in addition to also providing a separate mobile phone. With PTT, one device would suffice for both roles. Vodafone also points out that its PTT phones can roam internationally, something RT equipment cannot do.

Any operational tips?
Yes – as PTT is not a simultaneous two way technology, users may want to get to grips with military style communication methods, where one user says “over” when they have finished speaking, so the person at the other end of the conversation knows it is their turn to talk. The person talking always ‘has the floor’. Two people will not be able to talk at the same time. Also, when buying a PTT phone, be sure it has a very loud speaker, as you will need to clearly hear a voice, when a PTT conversation is initiated. Vodafone recommends a 90 decibel speaker.

Of course with volumes like that you do not hold the phone to your ear like a normal phone conversation – instead hold your mobile upright in front of your face. You don’t always need to talk to an entire group either, as PTT technology allows you to create sub groups and select just those people to push out to. You can also ‘log out’ of a group.

Also, be aware that PTT is not meant to replace traditional voice communications. While it will likely become an effective way of immediately enacting ‘burst’ style communication, it is not particularly good for conversations that require a frequent ‘back and forth’ style between users.

click to enlarge

Who is most likely to embrace PTT technology?
As PTT requires a defined user group to commit to a unified purchase simultaneously (a construction company, a taxi fleet etc) it’s likely that both Telecom and Vodafone will be going after the business market first. While there is nothing stopping anybody from buying a PTT phone, it requires an active user group to be of much use in PTT terms, so widespread consumer uptake will be slower.