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What is PoC – Push-to-talk over Cellular?The buzz surrounding a push-to-talk (PTT) facility is chiefly down to Nextel in the USA which has become the envy of rival operators. Nextel has increased its ARPU while simultaneously reducing customer churn and its uniqueness is its ability to offer push-to-talk. Nextel employs Motorola's iDEN technology to offer this facility. Basically it turns you mobile phone into a 'walkie-talkie'. In essence you select a user from the addressbook, press a button and say, "Hi this is Ground Control, over. " Although a 'real time' conversation is taking place, it is normally a data rather than voice connection. Unlike a standard mobile phone call, you can also 'broadcast' a call to multiple recipients. Most people are familiar with the PMR (Private Mobile Radio) systems which dispatch controllers utilise to contact their drivers/riders. With push-to-talk, couriers or taxi drivers would only need their mobile phones to stay in touch. In Europe the direct equivalent of Nextel/iDEN would be a network built on TETRA like Dolphin Telecom offers. However, the GSM network operators have spotted the opportunity. Back at 3GSM Cannes 2003, three infrastructure vendors – Nokia, Siemens and Ericsson – announced an alliance over the supply of push-to-talk services for GSM Networks. This initiative won immediate backing from two American network operators AT&T plus Cingular. [They're now the same company!] The technology then became branded PoC (Push-to-talk over Cellular). The objective was to use the IMS (IP Multimedia Subsystem) standard as defined by the 3GPP. This approach would allow a service to be offered using GPRS and then migrate it to EDGE or W-CDMA (3G). The idea was also to use existing location aware (presence) technologies, too. Then on 25th August 2003, the
specifications for PoC were submitted to the Open Mobile Alliance (which
incorporates the former WAP Forum) to build into a full spec. The idea was to
utilise existing 3GPP, OMA and IETF specifications. There were six major areas:
Requirements, Architecture, Signalling Flows, Group/List Management, and two
User-plane specifications (Transport and GPRS). This was, in fact, just a week
after Verizon Wireless in the USA launched its own push-to-talk service
utilising the Motorola V60p handset. It was the beginning
of a breakdown in the united front put up by hardware suppliers. In September
2003, a British retailer – Phones4U – effectively launched the first non-US
PTT service using Fastmobile's Fastchat software. By October 2003, Nokia had
announced that its own PoC solution would start shipping way before the OMA
would complete its work. The next month, Nokia announced its first PoC
compatible handset, the 5140. Another sign of fragmentation occurred when in
January 2004, Orange (owned by France Telecom) announced its Talk Now service
which didn't use PoC technology at all but instead utilised proprietary software
from Kodiak Networks. After
3GSM Cannes 2004, the battle lines started to be drawn up. Nokia announced, for
example, that it had done a deal whereby its PoC client software would be used
by Samsung for future PoC compatible handsets. In reply Ericsson, Motorola,
Siemens and Sony Ericsson said they were carrying out interoperability testing
against the OMA's specs which have subsequently come to be known as PoC Phase
One. Meanwhile Sony Ericsson has said it will acquire its PoC software from Sonim'. Previously
Sonim had forged a deal with Germany's Infineon, so that it's likely the client
will feature in handset using chipsets from Infineon which should include
Siemens. British based Sendo intends to market with handsets featuring a
built-in Sonim client, while an O2 xDA user can load the necessary software if
so inclined. Orange's Talk Now
works with the Treo 600 mainly because the software is supplied by Kodiak
Networks, a sister company to Handspring which invented the Treo. So currently the whole
Push-to-talk sector is in chaos. Tellingly supporters of the OMA specifications
say that the main feature still missing is the Network-to-Network Interface (NNI).
Without NNI is will be almost impossible for PoC handsets to roam onto other
networks. So it will be a re-run of the early days of MMS when the only users
you could message were subscribers to your own network operator. |
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