It's still a shockingly open question exactly how the world's carriers plan on transporting voice over LTE -- which is something everyone who loves 4G should be freaking out about, considering that it threatens launch schedules and interoperability among unlocked handsets. A vibrant array of possible solutions are currently on the table, including everything from SIP-based IMS (which is already approved by the 3GPP, helpfully) to the controversial thought of leaving legacy GSM and UMTS networks live for the sole purpose of running voice. T-Mobile International is putting its bets on VoLGA -- Voice Over LTE via Generic Access -- by participating in the VoLGA Forum, which has just published the second version of its specifications and aims for 3GPP consideration later this year. The technology routes circuit-switched (that is, old-school) voice over data packets, but the problem is that there are a bunch of companies proposing the same thing in slightly different ways; Nokia Siemens Networks, for example, is working on its own proprietary standard that'll go head-to-head with VoLGA. Currently, T-Mobile's the only major network actively participating in VoLGA's development, though it apparently has the support of every major infrastructure vendor except Nokia Siemens. Whether it's VoLGA or something else, let's hope everyone gets on the same page on the double before everyone gets too entrenched in incompatible technologies that make roaming difficult and handset variety lame.