Korea (South)

There are 3 major wireless telcommunications companies in Korea, and each have their own brand name for their wireless service:

- Korea Telecom, "KT" (Also known as "olleh", formerly "SHOW") - SK Telecom (Also known as "T") - LG Telecom (Also known as "LG U+")

Since 3G WCDMA is only supported by KT and SK Telecom, those are the two networks your phone will work on. LG Telecom supports CDMA only (similar to Sprint and Verizon)

Default data rate

 * Unknown

Data feature packs
Mobile data can be supsended if there is no airtime left on the SIM card.

Voice and SMS/MMS

 * National voice call rate: 4 Won/Sec
 * National SMS: 22 Won
 * National MMS: 220 Won

Availability

 * 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.)

SIM sizes

 * mini-SIM (2FF), micro-SIM (3FF) and nano-SIM (4FF) available.

Internet and MMSsettings
APN: alwayson.ktfwing.com
 * MMS Centre: http://mmsc.ktfwing.com:9082
 * MCC: 450
 * MNC* 08

More information

 * S Roaming site in English
 * Passport required.
 * Network: KT

Default data rate

 * 200,000 Won deposit
 * 7,700 Won per day (excluding 10% tax)

Data feature packs

 * unlimited

Availability

 * 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

 * S Roaming site in English
 * Passport required.
 * Network: KT

Default data rate

 * 200,000 Won deposit
 * 10,000 Won per day (excluding 10% tax)

Data feature packs

 * 500 MB limit per day.

Availability

 * 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

 * S Roaming site in English
 * Passport required.
 * Network: LG U+

In Korea, getting wireless service (and by association, a SIM card), requires that the subscriber have a Citizen ID number, or an Alien Registration Number (in the case of foreign nationals). This applies to both prepaid and postpaid service, and is mandated by Korean Telecommunication Law. For this reason, unlike in most other countries, it is not possible to just walk into a store and grab a prepaid SIM card.

The Alien Registration process takes about 3-4 weeks from the time of application, meaning it can take up to a month before you can freely sign up for a line of service.

Since there is no reason for a Korean citizen not to have a Citizen ID number, this is generally not seen as a problem by most companies, but it obviously creates a big inconvenience for visitors to Korea. Since the requirement is set by law, it's not possible to ignore it, but KT has created a way to deal with it.

With KT, it is possible to activate a prepaid line of service, with the only requirement being a passport. The service is usable for up to 90 days, which gives the subscriber plenty of time to get their Alien Registration Card (which is required for sojourns longer than 90 days anyway). Once you receive your Alien Registration Card, you can register it to the account and continue to use the prepaid line, or switch to a postpaid plan.

 Here is what you will do when you arrive in Korea: 

1. Take your phone to a KT Global Store, locations here: http://expatblog.kt.com/category/Lis...lobal%20Stores Coming straight from Incheon International Airport, it's probably easiest to go to the "Gwanghwamun" store. You can get there by taking the Airport Railway to "Gimpo Airport Station", then transferring to Line 5 (Purple Line) and getting off at "Gwanghwamun" Station, Exit 2.

The store is also one of our flagship stores, so it looks very nice

2. Present your iPhone and your passport, and ask to get a prepaid line activated.

'' Note: Korean phone systems work on a whitelist system, meaning that any phone unknown to the network is automatically disallowed from getting service. (Opposite of how most countries except Turkey work) This means that until recently, phones not produced in Korea were unable to be activated on a Korean network. This all changed earlier this year, meaning you can indeed use your foreign-sourced phone in Korea, but the customer service rep will have to request to have your phone added to the network, which can take around 30-60 minutes, give or take, depending on how the network is. ''

(KT has since switched to a blacklist system, meaning that any phone, given that it has not been reported lost or stolen, can be freely used on the network. To activate the phone, simple insert an activated SIM card into the phone and turn the phone on.  It make take a few minutes to register on to the system.  If it is not receiving service, try turning your phone off and back on.)

3. Receive a SIM card (also called a USIM card, but they are the same thing). Once inserted into your phone, your phone will be activated with a prepaid number, good for up to 90 days.

<span style="color:rgb(0,0,0);font-family:verdana,geneva,lucida,'lucidagrande',arial,helvetica,sans-serif;line-height:normal;">4. Apply for Alien Registration <span style="color:rgb(0,0,0);font-family:verdana,geneva,lucida,'lucidagrande',arial,helvetica,sans-serif;line-height:normal;">Since you said you will be in Korea for a year, you will have to apply for Alien Registry.

<span style="color:rgb(0,0,0);font-family:verdana,geneva,lucida,'lucidagrande',arial,helvetica,sans-serif;line-height:normal;">5. Once you get your Alien Registration Card ("ARC"), sometime within the 90 day period, visit one of the KT Global Stores and ask them to change over your account to the ARC, and also mention if you want to keep using a prepaid plan, or go with a postpaid plan.

<span style="color:rgb(0,0,0);font-family:verdana,geneva,lucida,'lucidagrande',arial,helvetica,sans-serif;line-height:normal;">For unlimited data, you will have to go with a minimum 55,000 won plan. <span style="color:rgb(0,0,0);font-family:verdana,geneva,lucida,'lucidagrande',arial,helvetica,sans-serif;line-height:normal;">The plan is called "i-Value", and includes: <span style="color:rgb(0,0,0);font-family:verdana,geneva,lucida,'lucidagrande',arial,helvetica,sans-serif;line-height:normal;">* 200 Voice minutes <span style="color:rgb(0,0,0);font-family:verdana,geneva,lucida,'lucidagrande',arial,helvetica,sans-serif;line-height:normal;">* 300 Text messages (Includes SMS/LMS/MMS) <span style="color:rgb(0,0,0);font-family:verdana,geneva,lucida,'lucidagrande',arial,helvetica,sans-serif;line-height:normal;">* Unlimited 3G data <span style="color:rgb(0,0,0);font-family:verdana,geneva,lucida,'lucidagrande',arial,helvetica,sans-serif;line-height:normal;">* Unlimited WiFi hotspot usage at any of over 50,000+ KT WiFi Hotspots nationwide (There are even hotspots on moving subway cars and boats that go up the Han river!)

<span style="color:rgb(0,0,0);font-family:verdana,geneva,lucida,'lucidagrande',arial,helvetica,sans-serif;line-height:normal;">There are a number of different rate plans that you can go with, and for that it's probably best to talk to one of the representatives at the Global Store so you can find one best tailored to your needs. Here is a list of the most common rate plans: http://www.ktexpatblog.com/?page_id=32

Information copied from: http://forums.macrumors.com/showpost.php?p=13051666&postcount=106