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The US does a lot of things differently: voltage, plugs and the mobile (here often called: cell[ular]) phone system too. This leads to a lot of errors and confusion when you come from a different part of the world. Here is a short guide to avoid disappointments.


This article applies to the 50 states and the District of Columbia of United States of America (USA). It's valid for all of the continental mainland and the islands of Hawaii as well. There, the same operators are on the air forming one common network without roaming fees. This is partly true for Alaska, Puerto Rico and the US Virgin Islands too, but additional operators offer mobile services there shown in own Puerto Rico (incl. US Virgin Islands) and Alaska articles. Other US overseas territories where different providers operate are featured in separate articles like these of Guam or Samoa.


The USA has 3 national mobile networks:

  • * Verizon Wireless
  • * AT&T Mobility
  • * T-Mobile US (inlcuding historic fourth provider Sprint since 2020)

A new fourth provider will be established by the satellite pay-TV company Dish.

This is supplemented by small regional networks operating in limited areas. Through domestic roaming agreements they are partly available to prepaid and postpaid customers of the big 4 providers too.

  • in 2G Verizon uses CDMA, while T-Mobile uses GSM. AT&T no longer operates a 2G network as of 2017 and only employs 3G and 4G networks
  • in 3G Verizon uses EVDO, while AT&T and T-Mobile employ UMTS-based technology
  • in 4G/"5GE" all operators employ LTE-based technology only
  • in 5G all operators employ 5G NR-based technology only

CDMA- vs. GSM-based networks[]

In the US, two different mobile network standards operate which were not compatible until 4G/LTE had arrived. The CDMA technology is used in very few countries of the world, such as Japan and China. But in the US, it was employed by two out of the four major operators - Verizon and Sprint. You could easily identify them by irremovable SIM cards, but this has changed now for LTE. Still, the device needs to be activated on the network and will be 'married' with the provider from then on with hardly any way to change (in the case of Sprint). You can still buy a CDMA phone or modem, but you can use it only on their network in the US and nowhere else.

The significant advantage of GSM based technologies is that the SIM card can be changed to one of another operator and country (except for SIM-locked devices). Only GSM technology enables you to perform the procedures described here and GSM is the only mobile technology used in 98% of the world's countries. This leaves you with a rather limited choice in the US as only two (physical) cellular networks and their resellers support GSM and its advancements: AT&T (in 3G and in some cases 4G) and T-Mobile US (in 2G, 3G and in some cases 4G).

Slowly, the gap between CDMA and GSM is narrowing as the same LTE technology is now used by both standards for 4G. CDMA operators now sell "world phones" with a SIM card slot, which work on GSM networks outside the US. Otherwise, GSM device owners still have very limited access to CDMA networks as shown in this sub-article "CDMA in the US".

AT&T vs. T-Mobile US network[]

You can count yourself lucky that you still have the choice, as some years ago T-Mobile US was to be sold to AT&T, but this was rejected by antitrust (competition) authorities. Superficially, it’s an easy choice. AT&T has more than twice as many customers and has the better nationwide coverage on 3G and 4G. But T-Mobile has focused on the big cities, giving better speeds there combined with very aggressive pricing well below the rates of AT&T. T-Mobile is the only 2G provider now and the 4G coverage gap to AT&T is narrowing.

Compatibility and frequencies[]

To really understand the differences, you have to compare the frequencies of your device with the frequencies offered by AT&T and T-Mobile as there are still a lot of incompatibilities with regard to devices from outside the US. For major phone models check against this list shown here. Keep in mind that some models with the same name are sold as different versions in the US versus Europe/Asia.


For 2G, you should have a phone that supports 850 MHz and 1900 MHz bands. From Europe or Asia a tri- or better still a quad-band phone does this. AT&T has shut down its 2G network nationwide as of January 1st, 2017. So T-Mobile remains the only player for 2G. For T-Mobile you need to have at least a 1900 MHz compatible device as it's their primary frequency.

On 2G you can only get EDGE with slow data speeds up to 200 kbps. If you want to use 2G for roaming, for example in dual-SIM phones, be sure that your roaming partner supports T-Mobile in the US or you will be shut out.

Support for 2G GSM is considered unreliable in much of the US. For more info, see


This is more complicated: AT&T has a good (though sometimes slow) coverage on 850 MHz and 1900 MHz up to HSPA+ (= 21 Mbps) speed, launched in early-2011. In most markets, they use both bands with aggregation for extra speed, but in some states they have licenses for just one of them. When checking frequencies on your device, be aware that 1900 MHz on 2G doesn't automatically mean that it's on the same band on 3G. Note that in North America, HSPA+ and DC-HSPA+ (and occasionally also HSPA) used to be marketed as "4G", a definition which is not accepted almost anywhere else in the world, while real 4G is marketed as "4G(/)LTE" or simply as LTE. Compare also with AT&T's marketing of aggregated LTE as "5GE" in the 4G/LTE section below. AT&T has announced that it will close down its 3G network by February 2022. AT&T will be a 4G and 5G network from 2022.

T-Mobile used to operate 3G on the 1700 MHz (= AWS) band only. This was (almost) the only operator in the world on this frequency, so hardly any non-T-Mobile US phone could cope with it. AWS is sometimes referred as “1700/2100” MHz suggesting a 2100 MHz (B1) phone would work. This is misleading as AWS uses the 1700 MHz spectrum for uploading and 2100 MHz for downloading, and can’t be handled by a band 1 only device.

Luckily, T-Mobile changed the game when it acquired new frequencies in 2012. They were now shifting (or “refarming”) the majority of their 3G spectrum from 1700 MHz (AWS) to 1900 MHz (PCS band). This gives much better compatibility with lot of devices like the iPhone. In 2014, the refarming was complete, and 1900 MHz HSPA+ (up to 21 Mbps) coverage is now in most markets, but few rural areas.

T-Mobile shut down 1700 AWS in most of their markets in 2015 and keeps on shifting more markets from 1700 MHz AWS to 1900 MHz PCS on 3G. In markets where 3G HSPA+ is offered on both 1700 MHz and 1900 MHz, T-Mobile offers DC-HSPA+ at speeds up to 42 Mbps on devices that support both bands, which are mostly only US-sold phones. So since 2016, for T-Mobile's 3G you need to have a 1900 MHz device; 1700 MHz has become optional for extra speed in some areas.

As far as the shutdown of 2G/3G is concerned, T-Mobile has adopted a different strategy. It's going to phase out 3G instead of 2G like AT&T. In 2017 it began to close 3G on 1900 MHz (PCS) and refarm its spectrum to LTE. This affects from 2017 these key areas located in:

Allentown-Bethlehem-Easton, PA-NJ, Boston, MA, Cambridge-Newton-Framingham, MA, Cincinnati, OH, Dover, DE, East Stroudsburg, PA, Elkhart-Goshen, IN, Florence-Muscle Shoals, AL, Hillsboro, TX, Lancaster, PA, Manchester-Nashua, NH, Providence-Warwick, RI-MA, Reading, PA, Rockingham County-Strafford County, NH, Sussex, DE, Tuscaloosa, AL, Waco, TX, Long Island, NY, New Jersey, New York, NY, Atlanta, GA, Bakersfield, CA, Cape Coral-Fort Myers, FL , Detroit, MI, Naples-Immokalee-Marco Island, FL, Orlando, FL, Port St. Lucie, FL, Santa Maria-Santa Barbara, CA, Seattle, WA, Tampa, FL, Ventura County, CA, Central PA: Scranton, Wilkes-Bare, Hazleton, PA, Dallas, TX, Jacksonville, FL, Las Vegas, NV, Trenton, NJ.

In all the mentioned areas like New York City, 3G has not been closed down yet entirely on T-Mobile, but works only on a legacy AWS (1700 MHz) band. Few devices from overseas can cope with 3G (not LTE) on 1700 MHz. This makes roaming plans without LTE options now quite useless.

T-Mobile has not specified an exact closure date for its 2G and 3G networks, but is is refarming frequencies from 2G and 3G to 4G and 5G. Nowadays, it is better to use 4G/LTE in the US for any data beyond messaging or maps and soon for voice too.


Things are even more complicated with LTE. AT&T started its 4G/LTE in 2011 on 700 MHz (B17/B12) and 1700 MHz (B4) depending on region added by 1900 MHz (B2), 850 MHz (B5) (refarmed from 2G and 3G), 1700 MHz (B66) and 2300 MHz (B30) later in some city centers. It's supplemented by additional 700 MHz spectrum on band 29 (B29) and band 14 (B14). It covers 365 million people (in the United States and Mexico) in 2016 in THESE areas. In 2019, it started to market aggregated LTE as "5GE". This is not real 5G, rather based on 4G and better known as LTE+ or LTE Advanced in the rest of the world.

T-Mobile started with 4G/LTE in 2013 on the refarmed AWS frequency of 1700 MHz (B4) and acquired licenses on 700 MHz (B12), 1900 MHz (B2) and 1700 MHz (B66) to reach 311 million people. The employment of 700 MHz in rural areas by T-Mobile has further broadened its coverage and reduced its gap to AT&T and Verizon. In the latest auction spectrum in 2017, new 600 MHz (B71) was acquired mostly by T-Mobile and they have started to deploy it from 2017 onwards to boost coverage in rural areas called "extended coverage". In 2020, shortly after the acquisition of Sprint, T-Mobile also began deploying 2.5/2.6GHz (B41) spectrum nationwide. This is currently mostly found in most urban areas but is quickly expanding into suburban areas throughout the U.S. T-Mobile also uses unlicensed spectrum in CBRS 3.5-3.7GHz (B48) and LAA 5GHz (B46) in dense, high traffic locations in some cities for increased capacity and speeds.

Be aware that the 700 MHz frequency used in the US is on bands 12, 13, 14, 17 and 29. These bands are all incompatible with the 700 MHz that is going to be employed or already in use in Europe, Asia, Australia and Latin America on band 28 (B28) because of different up- and download spectrum. Nevertheless, at least 4G/LTE is able to bridge the gap to CDMA (see Basics above and here) as both systems agreed on the same technology for 4G/LTE.

LTE compatibility of non-US devices[]

Unfortunately all mentioned 4G/LTE frequencies are hardly used for 4G anywhere else in the world and a phone from outside the US might be compatible with only a few of the frequencies used. The latest Apple and Android phones tend to have a much broader range of 4G/LTE bands, including the necessary US LTE bands. Check the specifications for your phone model number. The same applies to routers, tablets and modems, which are hardly available for US and overseas markets at the same time.

As an alternative, locally cheap disposable phones are sold (colloquially referred to as burner phones) at major retailers such as Walmart, Best Buy and Target. A cheap smartphone with LTE will cost anywhere from $20 to $100. It will work only in the US and nowhere else and is likely to be locked to the provider. On the flip side, most routers and modems are priced higher in the US than similar models in Asia or Europe.

VoLTE requirements (from 2021/2)[]

Both T-Mobile and AT&T are refarming spectrum from 2G and 3G to 4G/LTE and 5G. The old networks will be shut down. This requires your phone to support VoLTE (Voice over LTE) to make voice calls or you can only use VoIP apps like Skype, WhatsUp, Hangout and others for voice.

Starting in 2021, T-Mobile is going to prohibit all non-VoLTE capable phones from being activated on its network. This may limit the list of compatible phone models a lot. It's not yet clear if all their MVNOs will follow the same policy and ban all non-VoLTE phones.

AT&T goes even a step further as they are to close their 3G network by February 2022. They have issued a whitelist of phones that work with VoLTE (what AT&T calls 'HD Voice') on their network. This is going to limit the BYOD to a few officially approved phone models from 2022, unless AT&T changes its policy and accepts, similarly to T-Mobile, all VoLTE (or HD Voice) capable phones on its network.

This policy won't affect you when you use a roaming SIM card from overseas in the US, but only if you want to activate a local US SIM card on your phone. Nevertheless, without any 2G or 3G networks left in the country, your phone will need to support VoLTE if you want to receive or place usual voice calls also when roaming with a foreign SIM card on US networks.


The 3 national providers AT&T, Verizon, T-Mobile and Sprint all launched their 5G networks in 2019. All of them have launched 5G for prepaid subscribers. However, the 5G speeds can be much lower on some carriers in the US compared to other parts of the world due to 5G frequencies in use. Typical Nationwide/Extended 5G networks are only slightly faster than 4G/LTE networks at around 60-80 Mbps. Speeds on T-Mobile's Ultra Capacity network are about 300Mbps on average with peak speeds of over 1Gbps. On all three carriers' mmWave networks, peak speeds are over 1Gbps but are generally only deployed in small portions of some cities.

This is how it looks in 2021:

  • T-Mobile’s Extended Range 5G using n71 (600MHz) currently covers 305 million people across 1.7 million square miles and their Ultra Capacity 5G covers 165 million people and uses 5G bands n41 (2.5/2.6GHz), n260 (39GHz), and n261 (28GHz).
  • AT&T 5G covers 230 million US residents in 14,000 cities and towns using 5G bands n2 (1900MHz) and n5 (850MHz) and AT&T 5G+ using n260 (39GHz) and n261 (28GHz) is now available in parts of 38 cities in the U.S.
  • Verizon's 5G Nationwide network covers 230 million US residents and uses n5 (850MHz) and n2 (1900MHz). It also covers parts of 60+ cities with their 5G Ultra Wideband network using n261 (28 GHz).
  • Sprint switched on 5G in about a dozen cities on massive MIMO on n41 (2500 MHz).This has been deactivated by its new owners T-Mobile in July 2020 to be moved to the new T-Mobile network.

Please note as well that there are only a few devices for US 5G frequencies on the market so far, even in the US. Hardware sold in other parts of the world is very unlikely to work on these bands.

Frequency guide[]

Networks AT&T T-Mobile US
2G (GPRS, EDGE) closed down nationwide in 2017 1900 MHz

(closing down in some markets)

3G (UMTS, HSPA+) 850, 1900 MHz

= Bands 2, 5

(to be closed by February 2022)

1700, 1900 MHz

= Bands 2, 4

(closing down in some markets)


Advanced, 5GE)

700, 850, 1700, 1900, 2300 MHz

= Bands 2, 4, 5, 12/17, 14, 29, 30, 66

600, 700, 850, 1700, 1900, 2500/2600 MHz

= Bands 2, 4, 5, 12, 25, 41, 66, 71


{}= selected hotspots

850 MHz, 1900 MHz, {39 GHz}

= Bands n5, n2, {n260}

600, 2.5/2.6 GHz, {28 GHz, 39 GHz}

= Bands n71, n41 {n261, n260}

Map Coverage


In 2019, the merger of the T-Mobile and Sprint networks (the 3rd and 4th largest national networks) was announced and approved by the authorities in 2020. T-Mobile is moving Sprint's network and most of its customers to the "New T-Mobile" network keeping all of Sprint's spectrum excluding the 800 MHz band (B26). A new 4th nationwide network run by IP provider Dish will eventually be established.

US specifics[]

The following characteristics may be taken for granted for US residents and frequent visitors, but pose a challenge for newcomers:

Prices and taxes[]

As usual in the US, all prices mentioned below are without taxes. In most states, you need to add sales taxes of up to 10% to the stated prices. This applies to starter packs and top-up vouchers, locally called refill cards, sold over the counter. Even online top-ups on the websites of the providers are taxed additionally. A reliable workaround for many providers is the 3rd party top-up site of Callingmart. For whatever reason, they don't charge any tax and only a minimal fee of up to 2% on some operators, which can sometimes be waived by using promotional codes.

When it comes to phone calls, the US is unique in two respects. First, the receiving party gets charged for taking a phone call (either at pay-as-you-go rates or deducted from the receiving party's bundled minutes) and therefore if a receiving party does not have any credit remaining, the call will not be connected (or if the receiving party runs out of credit whilst the call is in progress, it will be terminated immediately). Second, the call is charged from the moment you dial, not the moment the other party picks up, thereby rendering the first minute effectively as a connection charge so ensure you have good cellular coverage and be careful when dialling.


In the US, a data bundle or package is normally referred as a plan. This is because most data plans or packages require a monthly base plan that already includes a data allowance. More data can often be added as an add-on. On the other hand, this means that it's hard to stop the monthly base rate while you are out of the country and can't use your plan. The only way is to let your account balance fall below the recurring base rate (while auto-pay is disabled), so it can't be automatically renewed. But thus your plan will be suspended after a few months and your number will be lost.


The simple fact that you already have an unlocked mobile device capable of US frequencies and only need a new SIM card (and possibly a 'plan', see above) from the provider is often called either BYOD or BYOP in the US. It stands for "bring your own device/phone" and sometimes involves a complex policy of which devices are allowed on a network. While Verizon has some restrictions and Sprint even more, on AT&T and T-Mobile networks you can pretty much use all mobile devices that technically work on their network.

Do keep in mind that, despite the openness of BYOD/BYOP policies for AT&T and T-Mobile, advanced features such as Wi-Fi Calling/VoWi-Fi, VoLTE or HD Voice may not be available or guaranteed for your device, and that it's better to check with the carrier you end up with whether your device will be compatible. This may be necessary if you plan to place phone calls in areas with LTE-only coverage, or are in an area where only Wi-Fi is available. Generally speaking, T-Mobile and its MVNOs are less restrictive about which phones can access such features, while AT&T and it's MVNOs do not allow VoLTE/VoWi-Fi on prepaid plans or non-AT&T approved Android phones.

Plugs and voltage[]

All power adapters for mobile devices can cope with both 110 and 220 Volts nowadays, but you may check beforehand whether "110 V" is written on it. So only the US flat-pin power plug can be a challenge for visitors from overseas. All round-pin plugs and even Australian flat-pin plugs need an adapter to fit. A 2-pin adapter is sufficient. These are available for around $1-$2 in cheap Chinese-owned stores, but some travel accessories shops might want to charge you $20+ for a set of these small plastic parts. If you don't go to a city with a Chinatown, you might want to bring it from your country or buy it on for example eBay beforehand.

Another thing you have to consider is that even the most basic replacement USB cable in the USA is likely to cost you about US$ 10+ in offline stores, not to mention premium prices of the more advanced USB Type-C or Apple Lightning varieties. So make sure you bring (and don't lose) your own charging cable from home.

More info[]

If you need further information about the US prepaid market, check out this constantly updated guide on Prepaid Phone News:


As long articles are hard to navigate on mobile devices, this US article is now split into 3 sub-articles according to network provider: AT&T, T-Mobile and its respective resellers as well as Verizon from the perspective of a GSM device holder.

Click on the logo below to choose network and relevant sub-page:

Prepaid resellers in alpha order: