The book is written by four people from the Swedish & Finnish arms of Ericsson Research, who are deeply involved with the 3GPP's new Multimedia Telephony standard, which is intended to underpin the long-term shift from circuit-switched voice to VoIP within IMS.
Lets leave aside for the minute the continued lack of a business case for IMS for cellular-only networks (another major European operator told me last week that aside from 'adjunct' fixed-VoIP, they couldn't see any major revenue opportunity or compelling new services).
Instead, lets think about different radio networks and their support for VoIP.
- WLAN. Standardised 802.11b WLAN networks have been supporting VoIP since 2001, albeit with proprietary voice & QoS mechanisms. The 802.11e QoS standard suitable for prioritising traffic like VoIP was finalised in 2005, and had been discussed since 2001 as well.
- CDMA: The specifications for EV-DO Revision A were approved in April 2004, with the earlier intention to create a separate voice/video technology EV-DV essentially having been sidelined. Subsequently, there has been a fairly concerted effort to support VoIP in Rev A, with Qualcomm & various other vendors and their top operators ensuring an end-to-end voice proposition is viable more-or-less from the start of Rev A deployment.
- 3GPP: Clearly, the future all-IP LTE (long term evolution) technology will need to support VoIP. However, the radio networks won't start to be deployed until (optimistically) 2010, with further dependencies on the upcoming SAE architecture and of course IMS. In the meantime, we have HSPA networks being deployed now (HSDPA plus HSUPA is just starting), with probably the enhanced HSPA+ coming down the line as well. HSDPA is part of 3GPP Release 5, and full HSPA (ie including HSUPA as well) is part of Release 6. Rel 5 was finalised in 2002, and Rel 6 in early 2005.
So it's not as though HSPA has been developed in a vacuum, without awareness and even early deployment of some forms of wireless VoIP. Which makes this line in the book's preface even more startling:
"it never occurred to me that there would be any interest in providing a high capacity voice channel over the HSPA channels we had created.... The outcome was surprising, when designing HSPA we had accidentally designed an air interface that was capable of supporting voice applications with higher efficiency than existing circuit-switched bearers"
Now lets ponder... what usually happens when a technology "accidentally" supports an unanticipated application? More on my thoughts on this over coming weeks.....
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