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Staying Connected: International Phones (GSM, 4G-LTE, etc)

From an international traveller's perspective, it doesn't matter how awesome your smartphone is at home if it can't connect to a local network abroad, specifically 4G-LTE. There are hundreds of other sites (like this tool from Android) that have great reviews on the various operating systems, build quality, cameras, processors, etc., but they all tend to gloss over the fundamental connectivity & compatibility issues. In this post, I'm going to explain how to find the right phone for your international travels so that you don't end up with the prettiest "brick on the block". If you already know the basics about GSM vs CDMA and want to skip straight to the 4G-LTE section below, Click Here. And if you don't care about all that and just want to see which 4G LTE bands are used by the iPhone 6, 6 Plus, iPhone 5c, iPhone 5s, Samsung S4, Samsung S5, Google Nexus 6 and Nexus 5, Click here for the chart. (Updated 31 Mar 2015 for Samsung Galaxy S6 in the Spring 2015 update.


One of the most complicated aspects of an international move is trying to determine what phone & telecom provider to use at your new location. Understanding terms like GSM, CDMA, quad-mode, and 4G-LTE frequencies as it applies to handsets, service providers, and countries will equip you with the knowledge you need to find a phone that works in the two (or more) countries you need it to. Will your current phone work in the new country, or would a new phone work in both a new country and the place you call home but now visit only on vacation?

A lot of these lessons I learned first-person and I hope to save you some of the same trouble. When I was in South Korea, I had a pay-as-you go phone that I bought off the guy I replaced there. In Germany, I had a T-Mobile GSM phone that I was able to take back to the United States and use simply by switching out my German SIM card for an American pre-paid SIM card. Now we're headed over to Saudi Arabia and smartphones & data are additional considerations. So, I've scoured the internet to identify nearly everything you need to know about how to select the right international smartphone for you (or at least I've found the links for the places that do). So here are the considerations and how to determine what applies to you, your phone, and the countries you want it to work in:


GSM vs. CDMA: Modes
At the basic level, it's the type of radio inside your device that determines which networks will allow you to connect. In the US, the major CDMA providers are Verizon, Sprint, U.S. Cellular and Virgin Mobile. The major GSM providers are AT&T and T-Mobile. Most of you probably already know this, but the essential difference is that GSM uses a SIM (Subscriber Identity Module) card and CDMA does not. That said, GSM is also the standard in most of the world, with significant penetration in to the US, the bastion of CDMA. Switching GSM networks (i.e. getting a German number) is as simple as inserting a
German SIM. Some phones have the ability to carry two different SIM cards so one handset can possess two different numbers. Check out Amazon's catalog of dual-sim, unlocked, quad-band world phones.

I was going to put a world map of GSM vs CDMA here, but I couldn't find any CDMA maps that weren't only of North America. That should tell you something right there. But here's a nice comparison of GSM and CDMA coverage in the USA that proves that both GSM and CDMA have roughly similar coverage:

For a non-technical metaphor (seriously, tech folks will cringe at this), the difference between GSM and CDMA is like buying an AM or FM radio that will work on one but not the other. You might also see CDMA phones with a built-in GSM radio referred to as "dual-mode" or "world phones", where the mode refers to the GSM & CDMA technologies (ie, AM/FM). I think that's Verizon's attempt at staying relevant in the GSM world. But don't let the "world phone" name fool you, there are still further considerations.

Bands: Frequency
Dual-band, Tri-band, Quad-band are all ways of saying that your phone will work in more places. Using the AM/FM analogy, imagine there is only one radio station in the world and it broadcasts on four frequencies. In the case of phones, those frequencies are 850/900/1800/1900 MHz.
GSM Bands: Purple=900/1800MHz, Yellow=850/1900 MHz
So, you could have "dual-band" phone that works on the 850 & 1900 frequencies that are, technically, international because they work in the North America and some parts of South America, but that sounds like a semantic argument to me. A true "world phone" should be quad-band so that it can connect to one of the 850/900/1800/1900 frequencies. Unless you're in Japan, in which case just get a Japanese phone and call it a day. Your greatest uncertainties on coverage will be with a tri-band  phone, as it might work well in one part of the world but not in another...just avoid tri-band.

Clarification between "Tri-mode" and "Tri-band". I found this distinction on a forum: Tri-mode is generally applied to CDMA phones and means it works on three modes: Digital 850, Analog 850, and Digital 1900. It runs in two frequency ranges (850/1900 MHz), therefore it's dual-band.  In comparison, Tri-band is 900/1800/1900 MHz. The first two are used in Europe, Asia, and many other places, while the 1900 is the one used in North America. Fun definition factoid: 800-900 MHz are the "cellular" range and not technically correct for the 1800/1900 MHz frequencies.

This section is actually why I felt that I needed to write what is otherwise yet another post on international phones. 4G is the wireless standard for smartphones and data, and that is accomplished using LTE (Long-Term Evolution) bands that are numbered from 1 to 44. They also have specific frequencies assigned to those bands, but enough tech talk. This is simply another way of saying that any particular country will likely only use certain bands and a given phone will only have a select number of bands it supports. Here's Wikipedia's convenient list of LTE networks, and a map that shows 4G LTE coverage. Per wikipedia: "Networks on the global LTE-bands 1, 3, 7, 28 (FDD-LTE) or 38, 40 (TDD-LTE) are suitable for future global roaming in ITU Regions 1, 2 and 3." More info on FDD-LTE vs TDD-LTE.
  Countries and regions with commercial LTE service
  Countries and regions with commercial LTE network deployment on-going or planned
  Countries and regions with LTE trial systems (pre-commitment)
In my case, looking to move to Saudi Arabia from the USA, I am keen on finding a phone that will support local network bands 3/38/40:

Operator Country Freq (MHz) Band Duplex mode Launch Date Cat.3 Notes
Mobily Saudi Arabia18003FDDFeb 2013

Mobily Saudi Arabia260038TDDSep 2011[19][592][593] Currently FDD-LTE in band 7
is not possible due to military usage.[594]

STC Saudi Arabia18003FDDFeb 2013

STC Saudi Arabia230040TDDSep 2011
Zain Saudi Arabia18003FDDJun 2012
Zain Saudi Arabia260038TDDSep 2011[597] Currently FDD-LTE in band 7
is not possible due to military usage.[594]

and hopefully an American GSM-provider's LTE bands (AT&T and T-Mobile for example): 2/4/12/17
AT&T United States700 b c17FDDSep 2011[160] [depends on CMA-Region][A 1][A 3]
Network upgrade to support band 12 and 17 by Sep 2015.[136]
AT&T United States1700 a b c4FDDSep 2011[160] [depends on CMA/EA-Region][B 6][B 5][B 1][132]
AT&T United States1700 d4FDDSep 2011[160] [REAG #3, 5, 7][B 2][132]
AT&T United States1700 e4FDDSep 2011[160] [REAG #5, 6, 7][B 3][132]
AT&T United States19002FDDDec 2013[161][162] [depends on BTA/MTA-Region]
Additional network to deliver more bandwidth.
T-Mobile United States700 a12FDDJul 2014(?)[199][200][201][202] [depends on EA-Region][A 2][134][203][204][205][206]
T-Mobile United States1700 d4FDDMar 2013[207][208] [REAG #1, 2, 4, 6][B 2][132]
T-Mobile United States1700 e4FDDMar 2013[207][208] [REAG #1, 2, 3, 4, 8][B 3][132][209][210]
T-Mobile United States1700 f4FDDMar 2013[207][208] [REAG #5, 6, 8][B 4][132]
T-Mobile United States19002FDDJul 2014(?)[199][202][211] [depends on BTA/MTA-Region]

Selecting the Right Phone

How to use this information? Well, for starters, it's possible that the phone has the hardware to support more bands than publicized, but the firmware won't let you get them. Think of the V-chip for TVs, same deal. I can't really help that, but it's important to recognize that many manufactures build US models that have different specs than their non-US version.


First example, the Google Nexus 5, per their website:

Google Nexus 5: 2G/3G/4G LTE
North America:
GSM: 850/900/1800/1900 MHz
CDMA: Band Class: 0/1/10
WCDMA: Bands: 1/2/4/5/6/8/19
LTE: Bands: 1/2/4/5/17/19/25/26/41
           Rest of World:
GSM: 850/900/1800/1900 MHz
(no CDMA)
WCDMA: Bands: 1/2/4/5/6/8
LTE: Bands: 1/3/5/7/8/20

So, given those specs, it would seem that the US model wouldn't work in KSA. Dammit. I really wanted a pure Android phone. Here's hoping that the Nexus 6 does.

Next contender: Samsung. There are so many variants of the Samsung Galaxy S5 I'm just going to list a few.

LTE 800 / 850 / 900 / 1800 / 1900 / 2100 / 2600: SM-G900F (Europe) Bands: 1/2/3/5/7/8/20
LTE 700 / 850 / 1700 / 1800 / 1900 / 2100 / 2600: SM-G900A (AT&T) Bands:1/2/3/4/5/7/17
LTE 700/850/900/1700/1800/1900/2100/2600: SM-G900T (T-Mobile) Bands: 1/2/3/4/5/7/8/17

The US version of Samsung S4 Galaxy on T-Mobile and AT&T, Quad Band GSM: 
LTE Bands:
1, 2, 4, 5, 7, 17
Band I (2100), Band II (1900), Band IV (1700/2100), Band V (850)

So it would seem that the North American Nexus gives more LTE bands than the Samsung S4, but neither have the ones (3/38/40) I am looking for. I'm also looking at the the newer Samsung S5, but I haven't been able to tell how it's configured yet.

So, reluctantly (I'm really not a fan of Apple), here are the specs for the iPhone 5c & iPhone 5s:

iPhone 5c & iPhone 5s
Model iPhone 5c (GSM)
Model A1532 (US) 
Model A1507 (Europe)
Model A1529 (Asia) 

 iPhone 5s (GSM)
Model A1533 (US)
Model A1457 (Europe)
Model A1530 (Asia)
LTE Bands: *=not all models
1 (2100 MHz) 
2 (1900 MHz) 
3 (1800 MHz) 
4 (AWS) *
5 (850 MHz)
7 (2600 MHz) *
8 (900 MHz) 
13 (700c MHz)* 
17 (700b MHz)* 
19 (800 MHz)*
20 (800 DD) 
25 (1900 MHz)*
38 (2600 MHz)*
39 (1900 MHz)*
40 (2300 MHz)*
The Apple iPhone 6 specs are out now, this site has more info.

UPDATE 1 Dec 2014: The Google Nexus 6 came out recently, and it looks pretty solid. Here is that info:
Nexus 6, North America:
  • GSM: 850/900/1800/1900MHz
  • CDMA Band Class: 0/1/10
  • WCDMA Bands: 1/2/4/5/8
  • LTE Bands: 2/3/4/5/7/12/13/17/25/26/29/41
  • CA DL Bands: B2-B13, B2-B17, B2-29, B4-B5, B4-B13, B4-B17, B4-B29
Nexus 6, Rest of World:
  • GSM: 850/900/1800/1900MHz
  • CDMA: not supported
  • WCDMA Bands: 1/2/4/5/6/8/9/19
  • LTE Bands: 1/3/5/7/8/9/19/20/28/41
  • CA DL: B3-B5, B3-B8


LTE (4G) Band Chart: If you prefer the table form (more details here), you'll notice that the same couple of frequencies keep popping up. So, just because your specs say you get LTE on 1800 and 1900, if it's not the right band, you may be out of luck. For me, the right bands include something from the US (2/4/12/17) and Saudi Arabia (3/38/40).

LTE Band (Freq in MHz)
Apple iPhone 6 (A1549/1586) &
 iPhone 6 Plus (A1522/A1524)
Apple iPhone 5c (GSM)
Apple iPhone 5s (GSM)
Samsung S6 (Spring 2015) Update
Samsung S5 Galaxy
Samsung S4
Google Nexus 6 (US/
Google Nexus 5
1 (2100) IMT
TBD  F/A/T US World US&World
2 (1900) PCS
3 (1800) DCS
F/A/T US & World World
4 (1700) AWS
A1532 A1533 A/T US US US
5 (850) CLR
F/A/T US US & World US&World
6 - see Band 19
7 (2600) IMT-E
A1507 A1457 F/A/T US US & World World
8 (900) E-GSM
F/T World World
9 (1800) UMTS
10 (1700) AMS

12 (700)

13 (700)
A1532 A1533 US
14 (700)

15 Reserved

16 Reserved
17 (700)
A1532 A1533 A/T US US US
18 (850) 

19 (850)
A1532 A1533 World US
20 (800)
F/ World World
21 (1500) 

22 (3500) 

23 (2000) 

24 (1600)

25 (1900) 
A1532 A1533 US US
26 (850)
27 (850)
28 (700)

29 (70)
30 (2300)
31 (450)

32 not assigned

33 (2100)

34 (2100)

35 (1900)

36 (1900)
37 (1900)
38 (2600)
A1586/A1524 A1529 A1530
39 (1900)
A1586/A1524 A1529 A1530
40 (2300)
A1586/A1524 A1529 A1530
41 (2500)
A1586/A1524 US & World US
42 (3500)

43 (3700)
44 (700)


Locked Vs. Unlocked
While this is probably more of an American problem than anything else, it's still worth mentioning since most of my readers are American. The manufacturers of the phones don't care what network you run their device on. The service provider that enticed you to buy a massively discounted phone on their contract plan does care what network you run it on. They want you on their network. That's why they lock it when they sell it to you...If you try putting in a SIM card from a different service provider, it won't work. When I had my German T-mobile handset& SIM, I was able to swap in a US T-mobile SIM and have it work because it was still on the same provider (T-Mobile). If I put in an AT&T SIM, it wouldn't have worked. Unlocking a locked phone usually voids the warranty from the service provider (because they use that as incentive for you to not unlock it).

So, really, what you're looking for is an unlocked, quad-band GSM (or dual-mode) phone that runs as many LTE bands as you can find. In a straight head-to-head, Apple's iPhone 5 (A1532/A1533/A1507/A1457) and the US versions of the Samsung Galaxy 5 (T-Mobile's SM-G900T and AT&T's SM-G900A) appear to be the most useful abroad

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