Cheat Sheet: Push-to-talk

Yet another mobile voice service...

Heard a lot about it this year. Something to do with walkie-talkies?
It's understandable that people use that phrase. Push-to-talk (PTT) is a technology where you literally push a button to talk, just like on a walkie-talkie, and another party or parties listen. (That's called half-duplex because only one person can speak at a time - but don't worry, that's about as technical as I'm going to get.) Push-to-talk over cellular (PoC) is when a mobile, cell-dependent device is used. Going back some years there have been other PTT systems, in certain industries, using fixed lines.

So is that the difference between PTT and PoC?
In a word, yes. And let's face it, if we're talking telecoms, PTT can be a confusing phrase. But let's not go there.

Indeed. So why should we care for another voice service?
You hit the nail on the head with the phrase 'voice service'. Voice has clearly been the main application of telephony since its inception. And in spite of all the talk from mobile operators about SMS and other types of data communication, voice is still their big cash cow. But this is a type of voice service that uses data networks.

This is partly about a sell to end users - and let me come back to that in a second - but PoC is also about a business model for operators. We now have big equipment vendors such as Motorola and Nokia telling their network operator customers how PoC will mean more revenue. It will be about how they can use CDMA networks or GPRS extensions to GSM networks to carry voice messages.

But can't I send voice messages anyway?
You probably can. But PoC has several advantages over other types of voice services. Because of the way it uses networks, end users - as with instant messaging applications - can create 'buddy lists' of other users. That means they can see when someone is available - that's called presence.

Then of course they can call one-to-many. Imagine a group of people spread out - hikers in a forest or business people at conference trying to meet up - all keeping in touch.

Operators, for their part, will also say end users only pay for the precise time they speak, rather than the 'quiet time' when someone listens on a regular call, but that will also depend on each network's charging structure.

Who will use it?
Good question. The example that is trotted out time and time again from the US - where PoC is at a more advanced stage - is of construction workers using Nextel's offering. ("Hey, anyone on the fifth floor got any more nails?") But analysts also see more than just blue collar or business use. They think teenagers will send messages back and forth where once they might have texted (prompting speculation about cannibalisation of SMS revenues) and families keeping in touch, valuing presence, instant communication and privacy.

Who is providing it?
On the equipment side, main infrastructure players such as Ericsson, Motorola, Nokia and Siemens are all involved in a big way. As usual, there has been some jostling with some industry insiders worried Nokia will try to use its muscle and make others kow-tow to what it wants to do. But most seem happy to work through OMA, the Open Mobile Alliance, and come up with technology that is compliant with IP Multimedia Subsystem (IMS), as defined by standards body 3GPP.

Then there are niche players. A company called Kodiak, for example, is Orange's PoC supplier.

Orange - aren't they already doing this?
Yes, living up to their reputation of often beating competitors to launches, Orange announced its PoC service (called TalkNow) at the start of this year and trials with organisations such as Pfizer, the RAC and Shell. That gives some indication of where it sees a market, though at the actual pan-European launch at the start of this month the operator was already talking about consumers and SMEs.

And how about on the handset side?
It should be noted that Orange's service, in partnership with Kodiak, uses a slightly different method to most of the PoC rollouts we will soon see. It means lots of SMS messages being silently sent between devices to establish presence. But the Orange launch, on the Treo 600 handset, highlights something very important on the handset side. Smart phones such as that can have PoC client software loaded (it's the sort of thing that makes them smart phones) and that will also be the case with most Symbian- and Microsoft Windows Mobile-based handsets. But there will have to be new PoC handsets for many users, especially consumers. So rollout will depend on how quickly end users upgrade.

Is this a gimmick or will it really catch on?
There's no doubt some people will want PoC. And operators will start to push it hard. They not only see increased revenues from calls made but also PoC sessions turned into regular calls or conference calls. Then there's increased loyalty as people build up buddy lists that only work on a single network and so don't want to switch - the dreaded churn.

There's no doubt there's a cultural issue too. Some users will find PoC calls invasive. There are question marks over just how well individuals will manage their presence status.

And the future?
There aren't lots of experts willing to stick their necks out, though it must also be said it's not a particularly high-risk option for operators.

And what's beyond push-to-talk?
Vendors such as Motorola are already talking about push-to-picture and push-to-video. You can see why when so many people now carry camera phones and so much money has been sunk by operators into 3G networks. But voice, as so often in telecoms, will come first.

Not at all.