Friday, June 19, 2009

Cell Phone Bands—A Question

The frequencies used for both ordinary phone calls and 3G connections are different in different countries—one set in the U.S. and some other countries, a different set in Europe and much of Asia. A phone that can use four frequencies for phone calls and three for 3G can work just about anywhere. With three for phone calls, it works well in some parts of the world, less well in others--because there will be some areas where the missing frequency is the only one supported. With two frequencies for phone calls, a phone works in either Europe or the U.S., depending on what the frequencies are, but not both.

This raises an obvious question: Why don't all phones have four and three? One possible answer is that additional frequencies are in some way costly, require more expensive hardware or use more power. That does not strike me as very likely, but it isn't a subject I know much about.

A second possible answer is that phones are being deliberately designed to work well in only one area, in order to enable some form of price discrimination.

Do any of my readers know the answer? From the standpoint of this consumer, the consequence of the limitation is that, not uncommonly, the phone I am most interested in is out in a European version but not an American version.


Anonymous said...

The upgraded version of a free phone (openmoko) that originally had four-band, now comes in multiple varieties of triband.

It may be that they decided it is not worth the cost to add the extra frequency. Explanation 2) seems unlikely in this scenario.

Tim Worstall said...

"require more expensive hardware"


Augustin Moga said...

It's been a while since you've been voicing your discontent towards the cell phone offering available in US... I'm wondering: what could be the reason that the market seems unable to satisfy your demands?

Are you an atypical customer for cell phones/handheld devices? Don't think so, judging by the decent demands I'm reading on your postings...

So, what is it? Why isn't the market reacting to the demand that seem to be out there?

Anonymous said...

It's definitely less expensive to build hardware which can transmit and receive in a single band vs multiple bands.

I suspect we haven't quite reached the point where you can print a cellphone chip that directly attaches to an antenna -- so there are going to be some discrete components between the chip and the antenna, and more components == more manufacturing cost.

given the margins in this business, and given that most phones are only used in a small geographic region it doesn't make economic sense to make them all quad-band.

Chris said...
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jdgalt said...

More frequencies do require more expensive hardware, but there's a bigger problem you need to be aware of.

The vast majority of phones sold by major US carriers come locked so that you can't take them with you to use on another carrier. And many carriers refuse to let you use an unlocked phone (bought elsewhere) on their services.

So for example, even if you buy an AT&T phone that is advertised as able to work around the world, if you take it to Europe or Japan and use it, you'll be paying AT&T's overseas roaming rates; you won't be able to take advantage of any better deals offered by local carriers except by getting another phone.

This problem does not exist within the EU (for its residents) because its competition laws forbid the carriers to lock their phones. There is a group agitating for a similar law in the US -- -- but I doubt they will be successful, because the major carriers are big media conglomerates with huge budgets to spend on lobbyists and bribes.

David Friedman said...

On the question of locked phones ... .

I can't speak to all carriers, but when I switched from AT&T to T-Mobile in order to get the G-1, I got (I think) two AT&T locked phones unlocked (for my wife and daughter), and T-Mobile had no objection to our using them on their system.

T-mobile wouldn't instantly unlock the G-1 for me to let me use it abroad, but after I had had it for some months I asked again and they sent me the unlock code. I haven't used it yet, since I haven't been abroad since then. But presumably it means that if I ever switch back to AT&T, I can take my G-1 with me.

So it looks as though T-mobile, at least, will let you use unlocked phones and will (eventually) let you unlock their phones. And many phones can be unlocked by third parties without the provider's help or permission.

Chris said...
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Anonymous said...

It definitely costs more. For a low-end phone every penny counts.

montestruc said...


You can buy unlocked GSM phones at reasonable prices on any of several websites. You can then get a sim card from ATT or T-mobile and not get a phone with it, or you can buy a pay as you go sim card.

I do that as when you travel overseas in some places you can get a sim card on a pay as you go plan cheap.

GregSJ said...

With regard to unlocking phones it is currently legal to break locking measures on phones that lock them to 1 carrier (at least until the copyright office revises the DMCA exemptions this summer.)

However I have been unable to find any information with regard to whether a carrier has to accept unlocked phones.

It seems to me that the DMCA exemption would be fairly empty if carriers were all allowed to re-create the same business model the exemption was created to destroy.

Henry Troup said...

The issue isn't totally obvious, since the four bands are two high (1800/1900) and two low (850/900), and each continent typically uses one high and one low. The frequencies are close enough that clever design could reduce extra hardware. I'm surprised that the costs of producing multiple versions don't dominate the cost of the added complexity. So many of the functions of a cell phone are really just different software using the same DSP hardware - that's why music phones are so common.

I recently got my quad-band GSM phone unlocked and was pleased to have everything work as advertised - a small cash payment got me a SIM and a UK number, instantly.

Daveon said...

It's largely an engineering problem exasperated by the US decision not to standardize around GSM when it had the chance in the 90s.

The US was extremely late to role out GSM services and when they came to, the spectrum that was used in the rest of the world was not available (900/1800). So the US had to use alternative spectrum - the 850/1900 bands.

As the US was late to the party and didn't have as many GSM subscribers the radio stack providers and the major phone companies just didn't bother with designing 850/1900 modems for their phones until much much later.

Actually designing a radio stack and getting working well is insanely complex. A modern 3G stack can have North of a million lines of C code in it. Then you have the hardware design issue of fitting multiple physical radios onto a single silicon stack. It's complex.

So the first Tri-Band devices with manual band selection didn't come to the market until about 2000.

Since then there have been a number of significant developments in radio layer design, however, it's still hard to get working and the quad band radios are a lot more expensive than dual or tri-band.

Quad core multi-mode 3G chipsets are becoming more cost effective so over time this problem will go away, or has already pretty much gone away on high end phones and this will trickle down into cheaper ones.

The problems with locked devices though are more business related and will be slower to disappear. They've largely been removed in Europe by the actions of EU telecom regulators but AT&T and T-Mobile US are fighting a real rear-guard action to stop the inevitable slide towards becoming nothing more than "bit pipes" to the consumer.

montestruc said...

I am curious, how high are the barriers to overseas telecom firms starting up in the USA? Is it more regulatory or more pure capital start-up costs?

I imagine the latter is important as you must have coverage of a wide area with cell towers to get in the game at all.

Daveon said...

montestruc: The capital costs of setting up a mobile network are staggering but there are also significant regulatory hurdles.

Radio spectrum is a finite resource so there are limits on how many carriers can offer services in a physical space.

Stephen Dawson said...

Free enterprise is glorious in the way it tends to optimise business practices and deliver the goods. But a tendency does not always mean perfection.

In another example of local business arms focusing only on the main game -- for no good reason -- concerns Sony Blu-ray players and the PS3. I understand that models of these sold in the US will not play any Blu-ray material which uses the 50 hertz signal standard employed in Australia, Europe, India etc. Yet identical models sold in those 50 hertz countries are all entirely comfortable with US/Japanese 60 hertz material.

All this is quite independent of region control issues, so to maintain two separate firmwares must actually cost Sony!

Francis Turner said...

The quadband hardware is currently more expensive than the various varieties of triband so low end phones tend to use a triband that has both bands for the geo area it is intended for and one of the others (and I think its always the 1800/1900 band that is dropped but I could be wrong).

Radio, at the level we're talking about, is horribly complicated and more an art than a science in many ways and cramming in the 4th frequency is a lot ore complex than it sounds like it should be.

This is going to change. Software radios that can support multiple bands (and even multiple standards) are being developed but at the moment they aren't in a form that fits in a handset.

Arianna Jane Calderon said...

Economically, it is advantageous to the cell phone producers. Technically, it is easier for the designers. Again, the competition for cell phone production is focused by region and not on the world as a whole. It means that for every person, one cell phone is not enough if he or she is going to travel. But, if he or she is on this location, what cell phone would he or she choose. Economically, that is good news to the industry.

iPhone 7 Rumors said...

There are two common frequency bands that all cell phone carriers use. The Cellular band commonly referred to as 1900 uses the frequencies 1850-1990. The other band is PCS which is the 800 MHz band uses frequencies in the 824-894 range. Most of our cellular phone signal products work on one or the other.