FAQ on Mobile Products

(Click on the questions to see the answers.)


Can I buy a prepaid SIM card for my phone?

Yes. In Korea, SIM cards are issued with activation of a line of service, meaning that SIM cards are issued at kt retailers nationwide. If you aren’t able to speak Korean, you can visit one of our many “kt Global Stores”, to have your service activated. Depending on the location, you can find a store that can assist you in activating your service in English, Chinese, Japanese, and even German.

In order to activate your service, you will need to have the following:

  • An unlocked, WCDMA 2100mHz compatible phone
  • An Alien Registration Card or passport

Important Note: Because of a restriction by the Korean Immigration Service, customers are able to activate prepaid service only after 3 days have passed since their entry into Korea. This means that if you were to arrive in Korea on the 10th, you will be able to activate your prepaid service on the 14th.  For this reason, SIM cards are not available at the airport, but at our Global Stores and KT retailers nationwide.

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How can I save on Prepaid Data costs?

If you are using a prepaid plan with a smartphone, chances are you may end up using a lot of data. While general prepaid data is metered at ₩ 0.28 per 0.5KB, you can save big on smartphone data by using one of our “Prepaid Data Plus” packages.

Just call our Foreign Language Customer Service Center by dialing 1583 (toll-free from your KT mobile phone), or (02) 2190-1180 from any other phone, or stop by any one of our KT Global Stores to have the package added to your account.

If you will be using a lot of data on a frequent basis, you can even have automatic top-ups set so you never have to worry about running out of data, or whether or not you remembered to add more credit.

Alternatively, you can use any one of over 110,000+ olleh WiFi hotspots nationwide, by grabbing an olleh WiFi flash voucher at most major convenience stores nationwide.

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Do I pay more for my phone if I don’t buy on installment?

When it comes to pricing, there are two separate parts, the cost of the mobile phone itself, and the monthly service charge.  There are two ways of buying the phone/tablet you want when you sign up for mobile phone service:  all at one, or on an installment plan.  Here’s how pricing works for each case.


  • All at once:  The initial discount is taken off the actual retail price of the phone, and you pay the difference at the time of sign-up.  Your monthly bills are will be just the standard charges for the rate plan you’ve chosen minus the rate plan discount you were offered for signing a contract, and are calculated as follows:  (Monthly rate plan – rate plan discount)

  • Installment plan:  The initial discount is taken off the actual retail price of the phone, and you pay the difference over the course of your installment period, usually 24 months.  Your monthly bills are calculated as follows:  (Monthly rate plan – rate plan discount)

As shown in the diagram above, the discount for the phone and the rate plan discount  is the same whether it was purchased all at one, or on installment.

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How do I check the remaining balance on my prepaid line?

You can check your prepaid balance either via ARS, or by a text-back service.

  • ARS:  Call 1500 (toll-free from your kt mobile phone) to reach our prepaid service ARS, where you can check your balance, as well as other details on your account.
  • Text-back:  Dial #0 + Send/Call from your phone.  After a short time you will hear a repeating tone, after which you will receive a text message with your remaining prepaid balance details.



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Can I use a phone that I brought from home? Do I need to register it?

As long as it supports WCDMA on the 2100mHz frequency, and it is unlocked, it should work on the KT network.

There used to a registration process, but as of May 2012, KT has changed over to a “blacklist” system, meaning that as long as a phone has not been reported lost or stolen, you should be able to bring it to Korea and simply pop in an activated Korean SIM card.

No registration required.

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I heard that Korea uses CDMA, does that mean my phone wont work?

In the era of 2nd generation mobile phones, aka. “2G”, Korea used the CDMA technology for mobile communications.

However, KT has since launched WCDMA (“3G”, different from CDMA) service, which means that phones on this standard are compatible with various 3G carriers throughout the world.

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Will my iPhone work in Korea?

The following models of Apple’s iPhone will work in Korea:

  • iPhone 3G
  • iPhone 3GS
  • iPhone 4
  • iPhone 4S
  • iPhone 5

The following models will NOT work in Korea:

  • iPhone (Originally released in 2007)
  • iPhone 4 – Verizon

Regarding the iPhone 5′s LTE capabilities

  • Apple has released the iPhone 5 in 3 different models worldwide, each supporting different LTE frequencies.  Although ALL models of iPhone 5 will work on KT’s network for voice calls, text messaging, and 3G data, only the A1429 (GSM and CDMA) models will allow for use of 4G LTE data speeds.


Please note:  All iPhones must be “unlocked” before they will be usable on KT, or any other network.  If you are unsure if your phone is unlocked, please inquire with your carrier’s customer support.  KT cannot unlock phones locked to other carriers.

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What does it mean for my phone to be “unlocked”? How do I know if my phone is unlocked? Can KT unlock my phone for me?

The term “locked” or “unlocked” refer to whether or not a phone is “locked” for use only with the carrier it was bought on. This means if your phone is “locked” to the carrier you bought it on, you cannot use it on KT, or any other carrier’s network. (The phone will not accept our SIM cards.) The easiest way to know if your phone is locked is to try another carrier’s SIM card in your phone, or to call your carrier and ask.

To “unlock” a phone means that a carrier has removed this restriction, and the phone can be used with other carriers, including KT. By nature of the process, only the carrier who sold the phone can unlock it, meaning that unfortunately, KT cannot unlock phones that are locked to another carrier.


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What is a “membership card”?

A membership card is a special benefit that we provide as a “thank you” to our customers. KT’s membership program, “olleh club”, is a card that you can use to get discounts at many member retailers.

You can find more information and sign up for olleh club easily by visiting a kt Global Store or any other official kt retailer near you.

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How do I get help with subscription, service, and billing issues?

You can reach us through the following channels:

Customer Service Center (For Mobile Services)

1583  (Toll-free from a kt mobile phone) or (02) 2190-1180

Hours:  Monday-Friday (9:00 AM~7:00 PM)

Languages:  English, Japanese, Mandarin Chinese, Korean

Customer Service Center (For Home Services)


Hours:  Monday-Friday (9:00 AM~7:00 PM)

Languages:  English, Korean

Emergency Contact

Please report a lost or stolen mobile phone through the following numbers a when the Customer Service Center is closed.

From within Korea:  (02) 2190-0901 (Korean-language support only)

From outside of Korea: +82-2-2190-0901 (Korean-language support only)

Expat Twitter     @olleh_expats

This is kt’s official Twitter account to stay in touch with our international customers. Follow us on Twitter to get the latest news and information from kt in real time.

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