Unless the entire internet and print media are wrong, we're just over 12 hours away from the Verizon iPhone announcement, yet many questions remain about unlimited data, tethering, mobile hotspot, simultaneous voice and data, and international roaming.

Will any of these be supported by a Verizon iPhone? Some of them? None of them? Let's take a look.

Unlimited data

We've already had a leak about unlimited data on the Verizon iPhone. Despite rumblings to the contrary it looks like, for now, Verizon is confident enough in their network to use unlimited data as a way to compete against AT&T's 2GB cap.


iPhone has support tethering since iOS 3 but it took until iOS 4 for AT&T to offer support. With tethering you connect your iPhone to your computer via Bluetooth or USB and your computer can access the internet via your iPhone's 3G radio. Will Verizon also try to be aggressive here and offer free tethering, will they take AT&T's route and offer tethering for a monthly surcharge, or will they simply not offer it at all?

Mobile Hot Spot

Unlike tethering, mobile hotspot turns your phone into a wireless internet router, just like a Mi-Fi, so instead of one device via BT or USB, you can connect 5 to 8 devices over Wi-Fi and share the 3G service between them. Sometimes there's also an additional charge for this, sometimes -- like with the Verizon Palm Pre Plus -- they've given it away for free.

iOS 4 currently doesn't provide for mobile hotspot so if Verizon is to offer it, there will have to be an iOS update as well. Since there will no doubt be a new CDMA/EVDO radio stack on the Verizon iPhone, perhaps new/different firmware is a given -- but will it be new/different enough to warrant a 4.2.2 or 4.3? Even if it does, would mobile hotspot come now and not be saved for an iOS 5 preview even in a couple months? And even with their network confidence, would Verizon want all iPhone users suddenly saddling up 5 to 8 other devices on an unlimited data plan?

Simultaneous voice and data

Currently Verizon's EVDO Rev-A 3G network doesn't support simultaneous voice and data. If you're surfing the web -- or doing anything else that uses data -- and a phone call comes in, your data connection gets dropped. EVDO rev-B supports voice and data but Verizon chose not to roll it out, jumping ahead instead to LTE which also support voice and data. The Verizon iPhone launching tomorrow probably won't have LTE and certainly won't have EVDO Rev-B, and while there's been some noise about simultaneous voice and data over an updated EVDO Rev-A network, there's been no evidence to data that Verizon has rolled it out.

So the Verizon iPhone probably won't support simultaneous voice and data which is bad news for anyone who likes to (or needs to) check email, look up directions, or just escape the boredom of a phone call by hoping on the internet. Since iOS 4 also introduced background data API for things like turn-by-turn navigation, it could limit the ability of cloud-based apps providing voice directions while you're on a phone call as well.

International roaming

Will the Verizon iPhone be a "world phone"? CDMA can roam on other CDMA carriers, but those are few and far between in a mostly GSM world. Since they don't use SIM cards, you can't even unlock them, pop in a local SIM, and avoid costly roaming charges. Verizon has launched combination GSM/CDMA phones in the past however, that came with a SIM card for use outside the US. That's a big plus for business travelers. Unless Apple has gone with a GSM/CDMA chipset like Qualcomm's, fitting two radios in one ultra-slim iPhone is probably a non-starter. That means you'll get to enjoy your Verizon iPhone inside the US but you won't be able to take it across the pond as anything other than an iPod.

Tune in tomorrow

We might get all the answers, some of them, or none of them tomorrow during Verizon's press conference. We may get them only before or even at launch. But until then, the questions remain. Are any of them deal-breakers for you?