Push-to-Talk:A New Way to Communicate 

Similar to with a walkie-talkie, you can listen in to group conversations and respond when you need to. But imagine if everyone starts using PTT... Is this a way of meaningful interaction or a new form of cacophony?

PTT (Push-to-Talk) has been in existence for a very long
time in the form of walkie-talkies. In a walkie-talkie system, everyone on the
same frequency hears each other and only one person can talk at a time. We can
also see these systems in our cities in the form of police dispatcher systems or
the systems used by radio cabs. Let's call these short voice conversation
'voice message' and users who are using PTT handsets as PTT users. So we can
define a Push-to-Talk system where users are allowed to send short voice
messages to each other at the press of a button.

Modern PoC (Push-to-Talk over Cellular) systems further
refine this approach. Modern PoC is a new real-time direct one-to-one and
one-to-many voice-communication service in the cellular network, involving
frequent exchange of short media messages. As the name suggests, the principle
of communication behind the service is same as that in conventional PTT. A group
of users can obtain and furnish their information and send short voice messages
to each other, if connected in a PoC session just by pressing a button. And more
importantly, with roaming feature of cellular networks, users can be anywhere in
the cellular network. The voice is sent almost instantaneously and the receiver
doesn't have to answer the call and is not charged like a conventional call
based on time. Instead the user pays for usage or the amount of data he
transfers over the network. Received voice can be played immediately or
delivered to user's Inbox and remains there until he decides to play it.

With PTT, instead of dialing a number and waiting for an
answer, the user just pushes a button, waits for the beep, and talks. And his
voice comes out of any and all his buddies' phones or lies in buddies' phones
in a mailbox to be played later.

Note: PTT and PoC are used interchangeably in this article.

How different it is

In the new PoC service from various operators, an icon on the phone's screen
indicates which of users' PTT contacts have their phones turned on, and user
can launch either one-to-one or group conversations like IM services on an IP
Network.

It has been observed that PoC users listen to the group
traffic while they are doing something else. This simple, real-time direct
communication serves the diverse needs of both business users and private
consumers ranging from controlled team management to spontaneous sharing of
experiences. It improves the conventional two-way radio systems by allowing the
users to have the entire globe as their PTT coverage area.

In some cases PTT can be handled entirely by the network
switches and handset may not need any application at all. Some such
implementations work in GSM networks. In other cases an application can be
downloaded on the phone and then phone becomes Push-to-Talk enabled. Also, some
phone vendors are trying to bundle Push-to-Talk functionality into their phones.

One of the biggest attractions of PTT is that users pay for
service not in terms of time but in terms of service usage. They are charged for
the amount of 'voice data' transferred between users and not the 'time'
for which user speaks. This is truly the beginning of usage based data-oriented
services.

PoC has several advantages over other types of voice
services both for users and carriers. Because of the way it uses networks, end
users-as with instant messaging applications-can create 'buddy lists' of
other users. This means that they can see when someone is available-called
presence. Also they can have short one-to-many conversations without going
through cumbersome conference set-up procedures.

The new walky-talky service via mobile networks simplifies
communication with friends or at work and brings a new element of spontaneity to
mobile communication. Arranging last minute appointments, spreading information,
coordinating tasks, or simply staying in touch: with Push-to-Talk it's all at
the push of a button.

Such short one-to-one conversations easily graduate into
calls between users and one-to-many Push-to-Talk sessions graduate into
conference calls if needed. PoC offers several benefits over traditional
voice-conferencing methodologies that make it particularly useful for
time-sensitive, ad hoc voice calls that don't require extensive discussions.
Most PoC calls are several times shorter than regular cellular calls but usage
levels grow rapidly, and the number of call minutes at the end of the month may
be higher, so operators can expect to see growth in ARPU (Average Revenue Per
User).

Although a connection cannot always be guaranteed, the use
of personal, handheld devices, presence management, and 'one-number'
(multiple device signaling), etc can maximize successful contacts.

Challenges

For implementing and operating PTT many other issues must be considered and
ultimately resolved/managed for success. These include:

Call-Set-up time:
This is the duration of time from the instance of selecting a user to engage in
a PTT session, to the time that one is able to initiate a conversation. This
needs to be kept to a minimum, else the whole objective of the service is
defeated.

PTT interoperability:
Currently, PTT implementations are strictly proprietary, creating a situation in
which there is little or no opportunity for interconnection between PTT systems.
Thus, no inter-carrier PTT communication for end users.

Numbering issues:
An example for this is that one decision point is whether to use a single number
(for both normal cellular and PTT) or a separate number for PTT calling.

But, just like most new features, early adopters could face
some difficulties. To start with, Push-to-Talk services on different networks
might not be compatible with each other. But these early adopters will always
have the early starter advantage and be pioneers in this new way to communicate.

But PTT definitely has a bright future. In the US, where
according to a study by market research company Zelos, PTT ranges in second
place among desirable mobile phone features, directly after a color display. But
PTT will penetrate the whole market only if information can be exchanged easily
between the different mobile networks and devices. This will be one of the main
challenges PTT faces in future. Another downside is that mobile phones are
already too intrusive both to the individuals carrying them, and also to those
around them. Instant calls with several parties involved could quickly
degenerate into confused cacophony. But, most enterprise employees have managed
to cope with the open plan office without shouting at their neighbors, and most
group meetings can be managed effectively.

This new category requires a new etiquette, perhaps not
'over and out', but 'the caller is 'IN'', and 'me next'. In addition
to exploiting the instant capability of the telephony network, it can use the
additional data communication to indicate state. That means more states than
just 'busy' or 'off', and further in-call indications of requests for
interruption, termination and perhaps even voting. Checking presence prior to
call initiation might even be useful in regular one-to-one phone conversations.

The future

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 or conference calls. And when people build up buddy
lists that work across mobile networks, they certainly have more loyalty to
their network-service provider and so there are fewer chances for them to switch
their identity in the user community-the dreaded churn. There's a cultural
issue also. Some feel that PoC calls will invade our privacy. It's still a
question that how well the individuals will manage their presence status and
avoid becoming privacy intruders.

Beyond Push-to-Talk

Vendors such as Motorola are already talking about Push-to-Picture and
Push-to-Video. It makes perfect sense. When so many people now carry camera
phones and operators have sunk so much money into 3G networks, it makes all the
sense to make use of this investment and use presence infrastructure created for
PTT to create new service like Push-to-Show and Push-to-Picture. But voice, as
so often in telecom, will come first. So PTT is soon going to grow into a family
of services based on present infrastructure and have many siblings like
Push-to-Show and Push-to-Picture. Online gaming, active phone book, the list
goes on and on.

But let's think whether PTT is only about sending
messages from one phone to another. No. In fact it is just a part of
collaborative communication between working team or collaborative groups. It is
about a new kind of communication mode being adapted by the users beyond the
conventional calls.

Himanshoo Kumar Saxena, Software Architect, Induslogic