Korea (South)

Basics
The Republic of Korea (= South Korea) has 3 mobile network operators: supplemented by many MVNOs on the three networks.
 * SK Telecom
 * kt olleh (by Korea Telecom)
 * LG U+

South Korea can still be a tricky country to buy a local SIM card. There never have been any 2G/GSM networks and some legal regulations still impede the use of a local SIM card like in many other countries. That's why some WiFi and "WiBro" operators and rental agencies are listed at bottom of the list as an alternative.

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 US phones only support 850 or 1900 MHz.

SIM cards of the major providers are sold in the operators stores, SIMs of the MVNOs rather in convenience stores like CU, 7-Eleven and GS25 like in airports.

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 usual GSM devices.

SK Telecom and KT both work on 3G and 4G/LTE 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 WiFis and networks based on Mobile WIMAX technology, they call WiBro. 5G is scheduled to start in 2018 as one of the first countries.

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 (by KT - 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 WiFi vouchers for their WiFi hotspots. At Incheon airport, KT has several service desks in the arrivals hall where you are likely to find signs advertising SIM cards (as do the other mobile network operators - SK and LG+).

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 all of their stores. Each top-up amount involves a validity period. Purchase and booking of packages is easiest in their global stores (list of locations). However, note that this SIM can't be purchased at Incheon International Airportm but there are other SIMs you can get on the KT network at the airport). 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 3G/HSPA+ & 4G/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 SIM cards are available only with the 4G option.

These monthly packages can be booked on the card (for 3G HSPA+): These monthly packages can be booked on the card (for 4G/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 WiFi voucher
Olleh runs the biggest WiFi 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: 1,100 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 or WiFi routers are: Data is an expensive 1.5 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.

More info

 * APN: alwayson.ktfwing.com
 * Website for rentals: http://roaming.kt.com/rental/eng/main.asp

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 pick-up locations and delivery too. 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 pick-up or delivery prior to arrival. You can order it online on their website either to be picked up at certain locations like train stations or airports, or to be sent to hotels or even abroad. They have many 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 KRW to any place in Korea and for 17,000-20,000 KRW to some countries in Asia and Australia. These monthly plans are offered (nano SIMs are 5,000 KRW more):

The official distributor www.egsimcard.com offers delivery to about 50 countries worldwide.. SIM cards are sold at € 9.95 for micro and € 10.95 for nano SIM plus € 3.50 for shipping and handling at these monthly rates: 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. These offline cards are sold for a surcharge summing up to 30,000-50,000 KRW (with less credit, because sellers charge an "activation fee"), and still need to be activated.
 * 500 MB: 11,000 KRW
 * 1 GB: 16,500 KRW
 * 2 GB: 22,000 KRW
 * 5 GB: 44,000 KRW

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 KRW per MB, WiFi is not available. You can add these monthly data packages (tax incl.): Also available for delivery or pick-up in Korea are the following monthly data/credit/SIM bundles (for standard & micro SIMs - add 5,000 won for a nano SIM):

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

Once you activate your SIM card in your phone, the WiFi 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 WiFi 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 better use a credit card instead. SIM cards have a 30-days validity. To extend SIM live, get it at their head office in downtown Seoul (map) or go there with a SIM bought at other places to get longer validity.

Technical Settings
Many phones like iPhones will pick up the correct carrier settings automatically. For credit check, internet booking and top-up you can download the EG SIM Android App. Its also possible to use the app for top-up with PayPal.
 * APN: alwayson.ktfwing.com
 * MCC: 450
 * MNC: 08
 * Server / MMSC: http://mmsc.ktfwing.com:9082

kt M mobile
kt M mobile by a subsidiary of KT aimed at tourists is operating on the 3G KT olleh network with good coverage. You need to have a GSM device capable of 2100 MHz UMTS or WCDMA. 2G or 4G/LTE does not work. They are mainly sold at airports and in tourist centers in convenience stores, but may be more expensive than other products sold downtown in the stores of the providers.

Availability
Prepaid SIM cards are available at Korean four major international airports (Incheon, Gimpo, Jeju and Gimhae) in the arrivals section in the convenience stores of CU and 7-Eleven chains. Of course, you can buy it in most CU, 7-Eleven and GS 25 around tourist attractions like Myongdong or Dongdaemun.

This provider also allows you order your SIM card online on their website before arrival and pick it up at certain locations in airports an unspecified lower price.

Activation
You need to go online and fill in the required personal information. It will be activated in less than 1 hour. However, if you try to activate it outside of their working hours (Mon-Fri: 9am~8pm, weekend and holiday: 10am~8pm), activation process will be completed after 9am on the next working day.

Data Price
They don't offer "unlimited data", but provide traditional prepaid SIM service (with voice and texts) all valid for 15 days only: To check remaining data amount, you need to call 080-770-0114 /1899-6283 / 070-4906-6283 (customer center).

Recharges
Additional top-up is available on their website. PayPal and international credit cards are accepted. Data is sold at 500 MB for ₩10,000. After an sucessful recharge, you will be notified by a text message. This top-up may take a day, if you do it outside of business hours.

Note that you can't extend the initial 15 days period of the SIM card by a top-up. You need to buy a new SIM instead.

Technical Settings
Many phones pick up the correct carrier settings automatically. If internet doesn't work properly, these additional manual settings are required:
 * APN: alwayson.ktfwing.com MCC: 450 MNC: 08
 * Server / MMSC: http://mmsc.ktfwing.com:9082

More information

 * Website: http://shop3.ktmsim.cafe24.com/ with additional info here

NeoKOSIM
NeoKOSIM is a startup company that has recently launched a partnership with KT to offer a 4G/LTE unlimited data access prepaid SIM card for travelers coming to Korea. This service appears to be almost identical to Linkkorea.co.kr (see below), except that rates are more expensive and you buy, not rent the SIM. So you are not required to return it.

Availability
You can order online on their website and will receive a PDF voucher via your e-mail after payment. SIMs can be picked up at Incheon airport, at the Olleh KT roaming center (gate 6) inside in the arrival hall 1F.

Prices

 * 10-day pass for US$ 36 (~ KRW 40,000)
 * 5-day pass for US$ 28 (~ KRW 30,000)

More info

 * APN: lte.ktfwing.com Server/MMSC: http://mmsc.ktfwing.com:9082 MCC : 45 MNC : 08
 * Website: http://www.neokosim.com

Link Korea
This company seems to be a subsidiary of KT Olleh. They rent (not sell like NeoKOSIM) 4G/LTE KT olleh SIM cards with unlimited 4G/LTE data:
 * rental for 5 days: 22,000 KRW (tax incl.)
 * rental for 10 days: 33,000 KRW (tax incl.)
 * rental for 30 days: 44,000 KRW (tax incl.)

Booking and pick-up
You'll need to book at least 2 days before your arrival to Korea. Book online on this page. They will contact you through email to get personal information and arrival date for registration. You can receive confirm e-mail. they will send you a detailed pick-up guide. Pick-up your SIM card at one of their pick-up points in Incheon Airport. Required deposit: by credit card open or in cash (100,000 KRW or 100 US$). Pick-up point at gate 6 Olleh Roaming Service Desk has 24 hours business hours. Enjoy mobile communication during your trip. Return it after use: Upon the return of the SIM card, the usage fee for calling and texting is calculated and paid by credit card or in Korean Won only. If a SIM card is not returned in time, a fee for the loss of the card (of 10,000 KRW) and the usage fee will be deducted from the paid deposit. The duration of rental can be extended by calling the service center.

More info

 * http://www.linkkorea.co.kr/sim/k-sim/

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 (for prepaid service) 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. 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

A prepaid SIM can be subscribed only at the SKT roaming center in the Incheon International Airport (located between Gate 6 and 7) at business hours 8am-6pm.
 * 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 (WiFi Plaza Korea, formerly S Roaming)
Mobile Pop a.k.a. WiFi Plaza Korea 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.

WiFi 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 7am and 4pm)
 * Airport Incheon: between gate 7 and 8 (opened between 6am and 10 pm)

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/

The Arrival Store
The Arrival Store provides cell phone and SIM card rentals in South Korea. Phone or SIM card can be ordered online to be waiting at Incheon Airport (with a delivery fee of 4,000-16,000 KRW or more) or to be sent to another postal address in Korea (for an unknown fee).

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

For longer term contracts they offer different rate plans for 3, 12, or 24 month rental contracts on SIM-only plans or with a phone included. Contracts operate on the KT olleh's LTE network and provide unlimited access to this operator's hotspots throughout Korea too.

Current rates start at US$ 37 per month for a 2-years contract with 300 MB/month and go up to US$ 97 per month for unlimited data in a 3-months contract. More rates can be found here .

The Arrival Store requires a 100% refundable deposit on phones and SIM cards. Deposits are ranging from US$ 40 to 150, and are only refunded via a Korean bank account or PayPal, that can be hard to convert in cash.
 * http://www.thearrivalstore.com