Korea (South)

Basics
The Republic of Korea (= South Korea) has 3 mobile networks: '''South Korea can be a tricky country to buy a local SIM card. There never have been 2G/GSM networks and legal regulations still impede the use of a local SIM card like in many other countries. '''That's why some WI-FI and "WiBro" operators and rental agencies are listed at bottom of the list as an alternative.
 * SK Telecom
 * KT (olleh is their brand name, Korea Telecom)
 * LG U+

Also, it's unlikely you will have any luck with CDMA service as phones are rarely sold outside Korea and very few other countries (like the US). The only real options for visitors are 3G/UMTS on 2100 MHz or 4G/LTE phones. If you are travelling from North America make sure your phone supports 2100 MHz on 3G as many phones only support 850 or 1900 MHz.

Frequencies
The 2G network of KT based on CDMA has been switched off in 2012, while SK Telecom and LG U+ maintains their CDMA networks (switch-off schedules not announced). There is a very good coverage on 3G up to HSPA+ speed with SK Telecom and KT on 2100 MHz and on 4G/LTE with all operators added by many WI-Fi hotspots in the country. Following table contains frequencies on both standards CDMA and GSM used by each carriers:

1 Primary LTE frequency.

Frequencies in italics are CDMA-only and not compatible with GSM devices.

SK Telecom and KT both work on 3G and 4G in the cities on frequencies used all over Asia, Australia and Europe. Forget about using CDMA with a foreign device: SK Telecom requires a lengthy process even for Koreans while LG U+ uses the 1800 MHz band as only carrier in the world for CDMA. You may still use CDMA roaming, if your phone/operator supports it (e.g. Sprint or Verizon devices from the US). Remember, 2G-only GSM phones as well as pre-OS10 BlackBerrys without 3G support don't work in S.Korea. On the other hand, if your device supports 4G, this country will have the best 4G coverage at almost 100%. Furthermore, Korea has an excellent network of open and commercial WI-FIs and networks based on Mobile WIMAX technology, they call WiBro.

Regulations
S. Korea had some legal restrictions in place which hampered your internet access, if you are not aware of them. You were allowed to buy a SIM card at arrival in the country, but immigration law mandates that your personal data needs to be entered into the system first which can take up to 3 working days. You were only be able to use your SIM card after this period. Since Oct. 1, 2015 foreigners visiting Korea can open a mobile account on the day they arrive at the country as the Ministry of Science, ICT and Future Planning and the Ministry of Justice have improved the foreigner identification system.

Furthermore, Korea used to run a whitelist scheme of accepting only certain certified devices to their networks based on their IMEI numbers. Luckily, this has been changed in 2012 to a blacklist approach. Before, no foreign phones could have been used in the country on a local SIM card without official approval.

Now, you still have to send a request to add your device to the network. This is done at the point of purchase. It can take 20 to 60 minutes, before your connection will be activated. That's why you should choose a designated device for your SIM card and tether from it instead of changing the SIM from one device to the other.

KT (olleh) Korea Telecom
Olleh or KT (Korea Telecom) is the public provider and 2nd network in the country with a good coverage (see above). It's a formerly public enterprise, is relatively cheaper than SK Telecom with the largest WiFi coverage in Korea and a well-organized prepaid plan available.

They have special stores called "Global stores" at airports and key city points where they support English-speaking service especially to foreigners. They have the broadest service in the country to foreigners: They sell prepaid SIM cards, do phone rentals with SIM cards, do "egg" rentals (see below) and sell WI-FI vouchers for their WI-FI hotspots.

KT olleh prepaid SIM card
KT's prepaid product is called "olleh simple" and can be loaded from 4,000 to 50,000 won at retailers like 7-Eleven, CU, GS25 or By the Way. Each top-up amount involves a validity period. Purchase and booking of packages is recommended in their global stores (list of locations) If you are unable to visit a global store then their English-speaking hotline can act as a translator for you.

You have to buy the prepaid card itself and it comes without any credit. Default data rate is 0.28 won per 0.5 KB. It's on HSPA+ & LTE. If you have a smartphone that supports the LTE bands that KT olleh supports (bands 3,5,8) then you can sign up for "olleh simple LTE". The SIM card costs 5,500 won for 3G (Olleh simple) or 8,800 won for 4G (olleh simple LTE). Nano simcards are available only with the 4G option.

The monthly packages can be booked on the card (for 3G HSPA+) The monthly packages that can be booked on the card (for LTE) Please note that LTE prepaid data rate is cheaper than 3G prepaid data rate. So sign up for LTE data, which will fall back to 3G HSPA+, if your phone does not support LTE bands.
 * 100 MB: 5,500 won
 * 300 MB: 8,800 won
 * 500 MB: 11,000 won
 * 1 GB: 16,500 won
 * 2 GB: 22,500 won
 * 4 GB: 38,500 won
 * 500 MB: 8,800 won
 * 1 GB: 14,300 won
 * 2 GB: 19,800 won

Also note that you must have some (greater than 0) amount of credit on your card, or else your data package will not work (and customer service may not know why!).

Olleh's extensive WI-FI network (see below) is added unlimited for free on the packages of 300 MB or more. You will need to connect to the secure olleh Wi-Fi network. It will ask you for authentication - choose SIM authentication.

KT olleh Wi-Fi voucher
Olleh runs the biggest WI-FI network with more than 100,000 WIFIs in the country, which is a very good alternative to mobile internet in the cities, but quite limited on the countryside (http://zone.wifi.olleh.com/#none). You can buy codes at many 7-Eleven, By the Way, GS25 or Mini Stop stores :
 * 1 hour: 1,000 won

A detailed guide how to log on in English is given here: http://first.wifi.olleh.com/en/aboutService.html
 * 24 hours: 3,300 won

KT olleh Rentals
For visitors, olleh rents smartphones and wifi routers too at their airport branches and flagship stores called "Global stores". Available phone types are iPhone5, Galaxy Note1(SHV-E160), Galaxy R Style (SHV-E170K).

They rent out different smartphones with SIM cards to use rightaway. The rental fees for phones are: Data is an expensive 5 won per 0.5 KB. But you can book unlimited data on 3G and 4G for 5,000 won per day.
 * 1-10 days: 3,000 won per day
 * 11-20 days: 2,000 won per day
 * 21-30 days: 1,000 won per day
 * over 30 days: free

Furthermore, they rent out "eggs". These are Mifi routes to build a local hotsport running on WiMAX tecnology. The rental fee is the the same as for smartphones with the same data pack.

Be prepared to pay around 200,000 won deposit for the rental or have it blocked on your credit card.

Technical settings

 * APN: alwayson.ktfwing.com

EG SIM
EG (for Evergreen) is a MVNO on the olleh / KT network with good coverage on 3G only and aimed mostly to visitors and tourists. They have English-speaking staff in their outlets and offer handy pick-up locations and delivery too. Even though olleh/kt has 4G LTE, EG SIM will only give you 3G coverage upon activation. However it is still pretty fast for most uses. But have in mind for this extra service EG is more expensive than buying a SIM directly from KT Olleh.

Availability
This provider lets you order your SIM card online already for pickup or delivery prior to arrival. You can order it online on their original website either to be picked up at certain locations like train stations or airports, or to be sent to hotels or even abroad. An mini/micro SIM is sold at 25,500 won, a nano SIM at 29,900 won at their website to be collected. They have lot of collection places like the international taxi booth or hotel information booth at Seoul (Incheon) International Airport, whose staff speaks English: (pick up locations). Delivery for additional 2,000 won to any place in Korea and for 17,000-20,000 to some countries in Asia and Australia.

Tourists from Europe can benefit a special promotion from a German redistributor when ordering through this site. In a special promotion until the end of 2015 all SIM cards are sold at € 9.99 instead of € 14.95 plus € 3 for shipping and handling to European countries only.

The SIM card is also available at these offline locations in S.Korea (map). When you arrive at the airport early or late, you can’t collect EG SIM card at collection places, but you will have to buy it at specific selling points directly. The offline cards are sold for a surcharge summing up to 30,000-50,000 won (with less credit, because sellers charge an "activation fee"), and need to be activated.

Activation
This is only necessary for offline bought cards. For this you need to go on the website here and fill in some data. Activation can only be done at business hours Monday to Friday and when you are in the country for more than three working days already. Wi-Fi needs to be activated separately (see below).

Data charges
Default data is 55.8 won per MB, Wi-Fi is not available. You can add these monthly data packages (tax incl.):

WI-FI
The packages include unlimited free olleh / KT Wi-Fi, which has the biggest network especially in the cities: Wi-Fi map. Passes for Wi-Fi only can be obtained separately (see KT / olleh article).

Once you activate your SIM card in your phone, the Wi-Fi registration is usually automatic. In cases when this doesn't work, you have to give your device details information, so that they will register you. For this you need to know your IMEI number and Wi-FI Mac Address, which you can find in your device settings. Log on or sign in your account at their website, go my account, check phone number and device specs, and click register. Registrations can only done Mon-Fri 9am-10pm and Sat/Sun 9am-6pm.

Recharges
To recharge you need to register on their website too. You can use any international Visa, Mastercard, JCB, AmEx credit or debit card. They say, that top-up cards are sold at 7-Eleven, C Space, GS 25 and Mini Stop, but many users had problems finding them. So use a credit card instead.

Technical Settings
Many phones like iPhones will pick up the correct carrier settings automatically.
 * APN: alwayson.ktfwing.com
 * MCC: 450
 * MNC: 08
 * Server / MMSC: http://mmsc.ktfwing.com:9082

SK Telecom
SK Telecom is the biggest mobile provider in South Korea. They are more geared to contract customers, have relatively good membership benefits, a good customer service and are more expensive than Olleh. SK telecom has recently added a prepaid plan for short term tourists. Like KT, SK also has counters at Incheon airport where SIM cards may be rented.

SK Telecom - PPS Plan
PPS Plan is designed for a foreign travelers to take advantage of its SK telecom network. You must first sign up for PPS rate plan which is as follows:

Data Plans (There is no official explanation whether it supports LTE or 3G only. There are contrasting reports from customers):
 * 30 day limit:
 * 300 MB: 8,800 won
 * 1 GB: 18,700 won
 * 2 GB: 24,200 won


 * 90 day limit:
 * 1 GB: 22,000 won
 * 2 GB: 27,500 won
 * 4 GB: 33,000 won

SK Telink - 7mobile
SK Telink is their consumer brand. But prepaid services are only offered by its MVNO 7mobile. Their prepaid plan T-Money has a base charge of 202 won per day and these monthly data packages to be booked: For 110 won per day, access to WIFI of T-Zone (http://www.twifi.co.kr/view/index.jsp) can be added.
 * 100 MB: 5,000 won
 * 500 MB: 10,000 won
 * 1 GB: 20,000 won
 * 2 GB: 40,000 won

SK Telecom Roaming
Similar to olleh Roaming, SK Telecom rents out smartphones and MIFI routers. Unlike olleh they focus more on the internet than some special stores to foreigners. The rentals can be booked online here: http://www.skroaming.com.

A smartphone is for 3,000 won per day and 6,000 won/day for 3G data up to 1 GB (overuse: 5 won per 0.5 KB) or unlimited WIFI for 2,000 won/day on T-Zone WIFI (see above). Discount is given to online reservations, long time rentals and returning costumers. Deposits are 300,000-700,000 for the devices.

The MiFi is given out for 3,000 won per day and for 5,000 won/day you get unlimited data on 3G and LTE.

Technical settings

 * APN: web.sktelecom.com

Mobile Pop (formerly S Roaming)
Mobile Pop was formerly called S Roaming and has now relauched. The similarity with SK roaming led probably to conflicts. It rents out devices on the LG U+ network (see Basics) which uses CDMA for 3G and LTE. Generally, it has not such a good coverage on the countryside as the two majors, but is fine in the cities too.

They don't rent SIM-cards only anymore. On a GSM device, they are pretty useless. Instead they rent out pocket WIFIs in 3G and 4G.

WI-FI rental
Their 3G WIFI router is for US$ 7.49 per day, their 4G/LTE router for US$ 9.49 per day plus 10% taxes. For service, they sell two packages with data: You need to give a 200,000 won deposit. Their rental offices are conveniently located at
 * 500 MB, 7,290 won airtime: 30,000 won + 10% taxes
 * 1 GB: unlimited airtime: 35,000 won + 10% taxes
 * Airport Gimpo: Terminal 3F (opened on weekdays between 7 a.m. and 4 p.m.)
 * Airport Incheon: between gate 7 and 8 (opened between 6 a.m. and 10 p.m.)

More information

 * http://mobilepop.co.kr/main/index.php?tpl_id=en in English

Prepaidphone.kr
They sell prepaid SIM cards for KT/olleh or SK Telecom to foreigners with a surcharge.
 * http://www.prepaidphone.kr/

Linkkorea.co.kr
They rent 4G/LTE KT olleh SIM cards with LTE unlimited data (taxes are included in the prices below): Order is online on their website to be picked up at Incheon airport or in downtown Seoul (but a reservation is not necessary if you just show up). SIM cards can be returned at either Incheon or Gimpo airports at their office downtown (strangely, SIM cards cannot be picked up at Gimpo). A credit card is required for deposit (and to post-pay for any phone calls and SMS), or a cash deposit of 100,000 KRW.
 * for 5 days: 22,000 KRW
 * for 10 days: 33,000 KRW
 * for 30 days: 44,000 KRW
 * http://www.linkkorea.co.kr/sim/k-sim/

The Arrival Store
The Arrival Store provides cell phones and SIM cards in South Korea. The phone or SIM card can be ordered online and be waiting at Incheon Airport (with a delivery fee of 4,000-16,000 KRW, or more) or sent to another convenient location in Korea (free?). Compared to picking up a rental SIM from one of the mobile phone companies at the airport (see the KT Olleh section), this may be less convenient and more expensive.

For short term travelers they offer unlimited calling, text and data (within Korea) for $5 USD (sim card) or $6 USD (iPhone 5) per day.

For longer term contracts they offer different rate plans on 3, 12, or 24 month contracts. If you have a phone you plan to use they offer SIM card only plans. If you need a phone they offer phones as well. The contracts operate on the KT LTE Olleh Network and as is common in the country they provide unlimited access to network operator hotspots throughout Korea.

Current rates can be seen here: http://get.thearrivalstore.com/phone-options/

The Arrival Store requires a 100% refundable deposit on phones and SIM cards. Deposits can be very large, ranging from US $40 to $150, and are only refunded via Korean bank account or Paypal.