Broadband voice pretty much means radio emulation through LTE devices. The first generation is being tested in production, where it can be tweaked to perfection in a beta environment where customers actually pay to have it (wow) and will likely pay for each revision (double wow). Harris just announced a product that will emulate P25 (presumably will create a P25 data stream that can port across from cellular to a native P25 system without going to baseband audio and signaling
http://forums.radioreference.com/co.../223905-harris-corp-s-beon-p25-radio-app.html. Then, another defense contractor has announced a similar product
http://forums.radioreference.com/co...rs-compatible-radio-waveforms-smartphone.html. These are apps, so they don't care if they're going over LTE, CDMA, GSM, etc., as long as it's going through some infrastructure into the cloud. The horses are on the track!
And GrumpyGuard, industry has a strategic plan to cover basically ANY eventuality. There's a multidimensional chess program running in their WOPR computers. Globally, divergent standards mean market-specific devices (P25 here, TETRA there, DMR introduced as an incompatible but more cost effective alternative, make the next version of P25 look like DMR); nationally, lobby for favorable regulatory environments and fund various interests; locally, get involved in bidding strategies and introduce products that have sole-source "enhancements" that thwart open, competitive procurement and marry the client to the manufacturer's product - even with an open "standard." The only interest most Congressional staffers have in telecommunications policy is how to use it to generate revenue. Speak about anything else and they gloss over, smile, and offer you coffee. Lobbyists and the pundits they pay off the street corner to corroborate their points of view only focus on one thing - getting the D-Block and everything else can be scorched earth, it's okay because "the only thing we'll need is D-Block" and "they'll get those problems [coverage/capacity in non-metro areas, recurring cost, and no off-network simplex mode] fixed once it rolls out."
The third dynamic are the proponents. Seems to me like most of the ones pushing for this have never worn a uniform, and, of the ones who have, have had a rubber gun and sat behind a desk for years. One has to question whether these folks are public safety's Nostradamus, or have bought stock and are trying to create their future wealth.
Finally, it's an infrastructure-based solution. We resist hardening because of expense. Is anyone really going to build something for double or triple the cost? We don't even have fiber connectivity in most parts of the country, let alone points of presence to plug this stuff into. It will only be as "hard" as its weakest link (or coverage).
LTE has its value. It's worth pushing for as a data service. But when some highly vocal people who might need to be selling Fuller Brush instead of what they're doing right now start taking tools out of the toolbox, handing us a hammer and telling us it's the only tool we'll ever need, remember it's still just a hammer (maybe with a beer bottle opener hot glued to it to justify the extra $3,000). It's not Doctor Who's sonic screwdriver. I think taking away everything else (mandated spectrum givebacks), or forklifting things that are in and working (not-too-old 700 MHz systems) is insane.