Today Deutsche Telekom (aka T-Mobile) announced the "worlds first VoLGA call". But really it was much more than that. DT showed the mobile industry a couple things about VoLGA:
First, it's relatively to implement, especially for vendors with a background in UMA. Not one, but two vendors stepped up with VoLGA Gateways, Alcatel-Lucent and Kineto. Presumably Ericsson could do VoLGA too, as they have a UMA/GAN controller as well. Remember, the VoLGA Forum went live in March 09, and here we are in December, just 9 months later, and there are two working systems.
For devices, this will become doubly important. Nearly all the major handset vendors (Nokia, Samsung, LGE, Sony/Ericsson, Motorola, HTC, RIM,...) have already implemented UMA/GAN. Modifying and simplifying that implementation to an LTE device for VoLGA support is very straightforward.
Second, for operators, VoLGA relatively easy to deploy. Presumably DT doesn't have extra lab resources laying around to make a lot of changes to the core network. The VoLGA Controller connects to an MSC through a standard 3G (Iu) interface. Clearly for a commercial deployment, there would need to be some element management system, but to make calls, the VoLGA systems only needed an Iu interface. Pretty simple.
Third, DT now has ALL their mobile services running over LTE. This isn't just 'dialtone', with years of additional work to actually turn 'dialtone' into a viable commercial mobile voice service. This is T-Mobile's commercial mobile voice service running on LTE -- all the standard and wacky telephony features (call waiting, forward, transfer, hold, conference,...) as well as the revenue generating Intelligent Network applications like pre-paid, toll free, and LNP. And certainly no need to run endless tests checking to see if the macro network 'falls back' the right way.
It is clear that VoLGA is the interim (and first) step on the way to IMS voice.