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Arthur M. Rosenberg

[May 18, 2004]


By Art Rosenberg

Converging Push-to-Talk At The Desktop?

The term “collaboration” is becoming increasingly popular to describe person-to-person communications between enterprise working teams and groups. Some pundits think of collaboration only in terms of real-time voice or video conferencing or requiring the online exchange of files and documents. However, all forms of personal contact and communication must be included in our definition of collaborative multi-modal telecommunications. (Let’s start calling it “MMT” for short, yet another acronym to remember!) For this reason, enterprise users will need converged and flexible alternatives for initiating, receiving, and dynamically changing the modality of their personal contacts.

Instant text messaging (IM) services introduced us to the “buddy list” and presence management for online immediate message exchange at the desktop. Unfortunately, implementations by the major service providers were not only “closed” and proprietary, but were aggressively kept shut by the likes of AOL. IM’s voice counterpart for mobile users appeared as “push-to-talk” (PTT) or “walkie-talkie” for cell phones using a different methodology for setting up group contact lists. It, too has been treated as a closed proprietary service offering. However, as enterprise personnel increasingly use both IM and mobile phones on new VoIP and Wi-Fi networks, we will need to bridge the communication boundaries between mobile and desktop users for exploiting “instant voice conferencing.”



We have a tendency to forget that there is really nothing new under the sun when you consider basic functionality of telecommunication technology. It’s just that when you change the environment, the appearance, or the procedure, you don’t recognize it anymore. So it is with the hot wireless service, “Push-to-talk.” In one respect, it is a descendent of the familiar “intercom” feature of traditional wired phone systems used in the enterprise where station sets could be directly interconnected by pushing dedicated buttons. It is also a descendent of older half-duplexed handheld radio systems where the term “walkie-talkie” originated.  In turn, we have these two forms of “instant” voice connections converging to join a multi-modal environment for VoIP networks.

PTT 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:

  • Faster initiation of group contacts – just pushing a button
  • Shorter calls by virtue of half-duplex exchanges, rather than full-duplex conversations
  • Anyone within a preset group can initiate the connection at any time
  • 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
  • Lower costs for usage based upon VoIP connections 


It should be pretty clear by now that any form of intrusive real-time contact will have to come under the control of some kind of personal availability and modality management. People can’t always be accessible for everything! To this end, visual text IM has successfully exploited presence management, letting contact initiators know if the recipient is online, idle, or away from their PC.

PTT services have also provided similar availability controls for the recipient and feedback to the initiator. This is particularly important because of ongoing conversations and new incoming voice calls. We expect to see PTT contacts become another limited multi-modal communication option that can be transformed dynamically, if required, into a full-duplex voice call. 

Of course, the basic Quality of Service considerations for any VoIP connection will apply and, where multi-party conferencing is involved, voice quality can be detrimentally affected. 

At the moment, current PTT offerings are limited to proprietary wireless carrier service offerings, some exploiting new VoIP connectivity. PTT is also focused on handheld wireless cell phones where the need for faster and less expensive contacts with mobile personnel is most pressing. However, enterprise (text) IM management is just beginning to take off, providing security and access control gateways to the leading proprietary commercial IM services. The interoperable convergence of these two capabilities combined with the power of device-independent SIP for end-to-end connectivity coordination, will support PTT as a faster and more cost efficient alternative to conversational voice calls. 

Part 2

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