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Thursday, June 14, 2007

OMTP IMS requirements - killing the "bearer agnostic" myth

I got a chance to wade through the OMTP's new IMS handset requirements document in full, on a flight yesterday. There's some good stuff - and some less good stuff in there.

Best of all is that it wants to make handset applications "bearer aware". I've been banging on about this for as long as I can remember. The notion that advanced handset apps on highly-intelligent devices should be ignorant of what network is being used as transport is ludicrous.
I've argued passionately & at length about why applications should behave differently over cellular and over WiFi, for example, because of different bandwidths, latencies, contexts, ownership, cost, security and so on.

I know that some handset ecosystem participants (eg Symbian) are already up-to-speed on this, and that some operators (eg BT) have also been ahead of the curve. So it's nice to see OMTP spell all this out in black and white as a standard requirement:

"IMS-1160 The UE MUST provide an API to allow an application to request the list of all available radio access technologies supported by the UE (e.g. WiFi, EDGE, UMTS, GPRS, etc)"

"IMS-1180 The UE MUST offer an API to allow an application to choose the bearer (from the list provided in IMS-1160) for a media connection subject to Bearer Policy."

I've given a lot of thought to the possible use cases of this type of capability, and it should significantly improve user experience.

(Incidentally - the "less good" stuff in the document? How much time & money is going to be wasted on implementing & testing the useless PoC capabilities of future phones? Why couldn't the OMTP have just killed that stone dead? Also... no mention of how to deal with multitasking-capable phones)


Steve said...

Dean, Interesting write-up. I actually came here specifically to see what you'd have to say about the spec.

One comment, one question:

Question: how do you see this all playing out with regard to different phones/platforms? In the US we are all eager with anticipation for the iPhone with its open development environment. OMTP is another open development environment, Symbian, WinMobile and even Linux have their own environments. How does this play out? Are these OMTP specs integrated into the phone's OSs? Does this become another layer on top of the existing layers?

Comment: the OMTP IMS middleware will run on UMA-enabled dual-mode phones. Note that UMA is a bearer, just like UMTS or EDGE. So when the app makes the API call to determine the bearer, UMA/Wi-Fi will be listed among the other technologies. Just reiterating the reason why UMA and IMS are complementary technologies.

Oh, and shameless plug for UMAToday.blogspot.com.

Anonymous said...

I'm interested in your comments regard PoC (which I presume you to mean PushToTalk)and why you think it's dead? is it IM that kills it or are call prices so low to eliminiate the need for PTT functionality?

Dean Bubley said...

Thanks for your comments.

UMAer - OMTP isn't really a development environment as such. It's a set of rules & specifications that are supposed to apply across ALL OS's and handset brands. In other words, Apple, Symbian, MS et al should produce OMTP-compliant OS's insofar as feasible. OMTP also specifies a bunch of other things more related to hardware, such as camera capabilities.

From your comment, I presume that means the API will list UMA/WiFi and also "local WiFi"? I have to say that I don't see UMA as "just a bearer" - it's more of a meta-bearer, where the underlying properties of the base bearer (speed, latency, control) are not necessarily transparent to the application. There may be some cases where this is useful, but generally I expect developers to want to know & choose exactly what physical bearer is being used.

Kerry - I'm a disbeliever in PoC generally, except in the US where historical accident has made PTT a fairly popular service. I cannot see any likely use cases in most of the rest of the world except for microniches like security guards.

Of course, there is a possibility that some Slovakian or Uzbek teenagers invent some hypercool PoC use case in 2011 when it's an unused feature lurking on everyone's phone & it takes off globally. But I'm not holding my breath. Apart from anything else, it has to work nicely for users with prepay billing (ie 80%+ of teenagers)

Mobile IM has its own problems, and certainly isn't strong enough to kill anything else, even something that's almost dead to begin with.