Push To Talk Over Cellular: Still Searcing The Flow Of Success

1. Push To Talk Over Cellular: Still Searcing The Flow Of Success Research Seminar on Telecommunications Business II Seminar presentation 12.4. 2005 Raili Koivisto Helsinki University of Technology

2. Contents • Introduction • Benefits for end-users and operators • Technology options and substitutes • Performance • Vendor and operator strategies • Pricing • Regulation • Conclusions

3. Introduction • PTT is a half-duplex voice service • PTT available since World War II with limited coverage but minimum charges • In 1996 Nextel begins to rollout iDEN • PTT in cellular networks is called Push-To-Talk over Cellular (PoC)

4. PoC

5. PoC building blocks • PoC Server for floor control and speech traffic • SIP IP Core for signalling • GLMS for group management • Presence Server • PoC Client in terminal

6. Benefits for end-users • Immediate wireless contact to a pre-defined person or group • Worldwide network • Suitable for group of friends, hunters, small businesses

7. Benefits for operators • Enables to compete with existing PTT services • Enhanced voice services • New usage models -> more usage -> increased ARPU in developed markets • New users in developing markets • Efficient way of using network resources

8. Technology options • OMA PoC by Ericsson, FastMobile, Motorola, Nokia, Siemens, Sonim • CDMA, GSM, WLAN, client-only implementation • IMS architecture based • iDEN by Motorola • Fast ”chirp to talk” times • Proven solution • QChat by Qualcomm • CDMA only • BREW client-only implementations • Circuit-based PoC by Kodiak Networks • Network agnostic • Circuit connection after call set-up -> cost, radio resource use

9. Substitutes • Conference call • No savings in cost or radio resource, slow to set up • Fastchat • Client integrated in Symbian • SKYPE + PDA + WLAN • Peer-to-peer, no central host, limited user base • Smaller savings in cost or radio resource Push-To-Talk over Bluetooth • Short range only • Free of charge • Hybrid with PoC possible • Instant Messenger solutions • Limited terminal selection

10. Performance • Circuit-switched PoC over 6x more expensive than PoC over GPRS • PoC over GPRS 5x more efficient, PoC over EGPRS 14x more efficient than over GSM • Latencies remarkable in GPRS • Voice quality on GSM level, BER quite high • Performance depends on end-to-end tuning

11. Vendor strategies • Several camps beside OMA standardization work, other technologies also further developed • Use of pre-standards to colonize markets • Clients available in phones • Trials with operators ongoing

12. Operator strategies • 35 operators using pre-standard solutions now, 14 of them using Kodiak in CS • Others waiting for OMA standard? • Or thinking positioning/pricing/target groups? • Or gathering money for new investments? • Or denying to cannibalize existing business? • Charging requires interconnection agreements • Lacking walkie-talkie culture in Europe

13. Pricing • OMA architecture supports several pricing methods • In US subscription fee includes certain no of minutes • In Australia normal call charge doubled • Simple pricing model encourages users • Pricing now – pricing in future

14. Regulation • Is PoC a voice service which should be regulated (legal interception)? • EU wants to encourage, not restrain diffusion of VoIP, FCC on same way but… • Privacy of user data, presence, location, group lists has to be regulated • Regulation needed for competition issues • Not applicable for emergency services

15. Conclusion • Technology push but no dominant design yet • High performance and worldwide interoperability require standard based solutions • Proven use case in US but does it work in Europe or Asia? • Is there enough attractiveness before multimedia convergence and virtual reality solutions?