Network operators looking to launch push to talk services not only have to evaluate the different vendor-specific solutions but must also decide on the delivery platform. The choice lies between the VoIP solution, delivered over the data network (referred to as PoC) and currently supported by the majority of vendors, and Kodiak's Real-Time Exchange solution. Depending on which vendor you talk to, each will have you believe its solution provides the best technology over which to offer the service. Unlike PoC, which runs over packet switched networks, Kodiak's solution is designed to run over circuit switched networks optimised for voice.
For the voice channel solution, push to talk uses an already existing and tested GSM network, allowing operators to leverage their existing voice network infrastructure, a point often cited by Orange in its defence of its choice of Kodiak's circuit switched solution (Orange announced plans to launch push to talk services using Kodiak's solution in January 2004). In using time slots to transport voice, as is the case when sending push to talk over a voice network, each call creates a circuit that reserves a line between two parties for the entire session of the call, whereas over packet switched networks bursts of data are only sent when needed and do not tie up an entire circuit. As such, looking at the issue purely from the perspective of network efficiency, the general consensus is that an IP based PoC technology, which uses radio resources more efficiently than an equivalent circuit switched push to talk connection, is more resource efficient. According to Ericsson, packet switched PoC is up to five times more efficient than circuit switched.
Despite the apparent inefficiency, however, of the circuit-switched solution, because it has two dedicated time slots open for sending and transferring voice, it provides immediate access and a much faster call set-up time. This equates to minimal latency in comparison to the latency that results from sending voice over a packet network with its inherent latency. Kodiak's Real-Time Exchange System boasts an intra-call latency of 150 milliseconds, thought to be better than Nextel's Direct Connect service, with intra-call latency of 450 milliseconds. Kodiak's call set-up time of 2.5 seconds falls short of Nextel's 1.5 seconds, but compares well with the other PoC offerings.
Even ignoring other technological differences and focusing solely on latency and efficiency, the issue may not necessarily be one of either technology being superior to the other, but could simply boil down to a trade off between bandwidth and latency. Thus in the case of Orange, its choice of technology may have been determined by its positioning strategy. In targeting the niche enterprise market with a premium priced service, as Orange announced in January 2004 that it would do, latency becomes paramount. A premium pricing strategy can only be justified if the operator is offering instant real-time services, as in the case of Nextel. At present Kodiak's solution offers cellular operators the minimal level of latency possible. An operator choosing to target the service at the mass market, however, might prefer to opt for a non real-time service with some level of latency that could most probably be tolerated because the service would be offered at a discount to standard cellular voice calls.
On the premise that European operators have generally held back from launching push to talk due to the unsatisfactory latency levels of the current PoC solutions (not to mention interoperability issues) and perhaps scepticism towards the available technologies, it would seem that deploying Kodiak's Real-time Exchange solution could give an operator a lead over its rivals. Though at present interoperability across networks remains an issue, Kodiak has indicated that it plans to offer an industry standard PoC server, which can be added it's RTX System, enabling operators to serve both PoC and Kodiak-enabled handsets.
Other than Orange, which is currently believed to be carrying out a phased deployment across 10 major European networks, US operator Alltel is the only other operator to have deployed Kodiak's RTX system. With each month that passes, the advantage Kodiak has over rival solutions diminishes as they continue to fine tune their solutions for optimal performance.
While most European operators are adopting a conservative wait-and-see approach, Orange's launch of push to talk over Kodiak's Real-Time Exchange will serve as a huge endorsement for the vendor's solution, should the service take off in a big way without any major hitches. Though only one handset, the Treo 600, has so far been presented, Orange plans to have 12 handsets available within its push to talk portfolio by the end of 2004. With a proportionate global subscriber base of 50,819,291 as at Q1 2004, Orange can leverage its position to ensure handset vendors supply it with handsets that meet its own specifications. In this case they must come embedded with the Kodiak push to talk client. Orange's moves in the coming months will not only serve as a catalyst for European competitors to launch their own push to talk service offerings but also a vindication of Kodiak's technology.
