Can a globe-trotting wireless speed demon be guaranteed 4G?

Life's list of tech frustrations has to include discovering that your new smartphone won't work wherever you need it.

That's especially maddening for world travelers, whether they're businesspeople, military personnel, students on study abroad programs or vacationers. The advent of 4G LTE promised to unite the globe under a common network technology. But the way different governments have allocated wireless spectrum has left the market fragmented. It's nearly impossible for manufacturers to give consumers what they really want: one device that can work anywhere.

Is there any hope for wireless globe-trotters? In this edition of Ask Maggie, I offer a suggestion on a pair of phones that might come close enough for now to being true global devices.

Dear Maggie,

I'm a Verizon customer with my account in suspension because I'm a US service member stationed overseas. The Verizon smartphone I brought with me doesn't work with the local provider, so I need a new phone. I'll be using it primarily here in Europe, so I want to be able to get LTE service. But I also want to use it when I go to the US and when I travel elsewhere. Is there a phone I can buy that can be used on any 4G LTE network in the world? If not, when do you think we'll see one?

Sincerely,
Stumped by the Specs

Dear Stumped,

The short answer to your first question is no. There's not one single phone guaranteed to get 4G LTE coverage globally. Instead, phone makers have to sell multiple versions of the same device for different geographic regions.

That's because wireless operators in different regions use different frequencies of radio spectrum for new 4G LTE networks. And for a device to work on a particular frequency, it must include a radio that's tuned to that frequency.

So why can't the operators worldwide use common frequency bands? There's simply not enough spectrum available in the same frequencies, and operators must use whatever slivers of spectrum they can get.

That's different from when 2G and 3G wireless services were first developed and there were more "airwaves" available for governments to allocate for cellular usage. For 3G GSM service worldwide, operators used only about 8 standard radio frequency bands. In contrast, for 4G LTE they use about 35.

"The way we have gone about globally shaking down more spectrum to use for 4G services has created extraordinary levels of complexity," said Mary Clark, chief marketing officer for Syniverse, which offers technology to wireless firms to help facilitate roaming among different networks. "We can fix battery life, device size, signal strength, and general power utilization in a device. But we can't create more spectrum."

Instead, phone makers have worked diligently to cram more radio technology into smaller spaces on devices, which lets them include radio tech geared toward a variety of frequencies. That's helped.

"Because of the bigger size of devices and falling prices, we are able to put more bands in the device," said independent telecommunications analyst Chetan Sharma.

One company has come close to engineering a single device that can be used globally. Apple offers versions of the iPhone 6S and 6S Plus that have a record-breaking 23 bands of 4G LTE. That's three more LTE bands than the year-old iPhone 6 and 6 Plus support. (Other versions of the 6S and 6S Plus have 22 bands, still pretty impressive.)

While these versions of the iPhone 6S and 6S Plus don't support every LTE band in every country, they come close, with some LTE access on every continent. They're the first smartphones to offer such a comprehensive array of LTE bands. They support the eight LTE bands used by the US' four major carriers, AT&T, Verizon, Sprint and T-Mobile. They also support the six major LTE bands used throughout much of Europe. They even offer LTE bands that let you get service in China, South Korea, Japan and some other parts of Asia.

With one of these phones, then, you should be able to roam onto a 4G LTE network in any of these regions. And if your phone is unlocked, i.e., if it isn't limited to a particular wireless carrier, you should be able to pop in a SIM card and get 4G LTE access from a carrier using any of those 23 bands offered in the region.

Not so fast...
The tricky part, however, is knowing which carriers in which regions use which LTE bands, and figuring out if those bands are supported in your phone. But even knowing that isn't guaranteed to get you seamless 4G LTE coverage. Even if a carrier supports a particular band and your device supports it too, the carrier may not have fully deployed service in that band. It's also likely that the operator has used multiple frequency bands to deliver service.

For instance, Verizon uses its LTE band 13 spectrum to provide broad network coverage, and it uses band 4 for greater capacity in densely populated areas like cities. If you had a device that lacked either of these bands, your service on Verizon wouldn't work optimally.

Sharma also cautioned that even though advancements have been made, phone makers must consider other factors when building a device.

"Sometimes it is just not practical to include some bands due to the varying economics and deployment plans in a given region or country," he said.

Instead, he said that within countries where 4G LTE is up and running, customers will likely get great access. And in places like the US, consumers will most likely be able to buy one device that works across all major carriers. But when these customers roam internationally, they'll probably have to roam onto a 3G GSM service rather than a 4G LTE network.

In other words, to answer your second question, Stumped, I'm afraid the dream of one device for the entire world is still a long way off.

Ask Maggie is an advice column that answers readers' wireless and broadband questions. If you have a question, I'd love to hear from you. Please send me an e-mail at maggie dot reardon at cbs dot com. And please put "Ask Maggie" in the subject header. You can also follow me on Facebook on my Ask Maggie page.