Korean Mobile Phones 101

Written by admin on June 5, 2008 – 5:19 pm -

One of the most frustrating things for a newcomer to South Korea is getting a mobile phone and services.  Majority of the foreigners are confused as to why their mobile phones from their home countries do not work in South Korea. The simple answer is that South Korea operates their mobile phones on the less universal CDMA as opposed to GSM which was adopted as a standard by most countries in Europe, Asia, and The Americas.

To make matters worse, the Korean CDMA frequencies differ from its North American counterparts. Korea operates in the 800 Mhz and 1800 Mhz band while North American CDMA providers such as Verizon and Sprint are on 850 Mhz and 1900 Mhz. The frequency differences do not pose much of a problem since majority of the new CDMA phone are multiband just like its GSM cousins. The problem lies in the fact that most CDMA phones until recently lack a SIM card. A CDMA phone has to be programmed at a service provider or phone dealer in order to get service.

The silverlining is that South Korean mobile phone operators SK Telecom and KTF have both adopted the the 3G UMTS WCDMA standard. So as not to get too geeky, this new standard is set to replace GSM. KTF and SK Telecom have been actively promoting 3G for the past few months which are branded as Show and T Service respectively.

This now allows foreign phones (Nokia, Ericsson, Palm Treos, HTC, Blackberries etc.) with global roaming activated from their foreign mobile phone providers to be used in Korea. The caveat is that your phone should be  3G WCDMA/HSDPA capable and you must be on a post-paid account with your provider. Why does it have to be a post paid account? Because pre-paid global roaming works a little differently. It’s based on a call back system. For example to call when roaming on a pre-paid account you dial a special prefix and the phone you want to call. You then hang up and wait for your phone to ring and upon picking up, the party you called will be on the other line and that doesn’t work in South Korea.

What about the rest of us who live in The ROK?

Now that South Korea is on the same page as the rest of the world as far as mobile phone standards, all we have to do is to buy a sim card from either SK Telecom or KTF and plug it into our foreign mobile phones right? Not quite, up until early this year the sim cards were locked to particular phone even within the same company, meaning it was not possible to take out the sim card out of your phone and put it into another phone. Even phones from the same Korean providers were sim locked, for example if I have an SK 3G phone with a sim and I decide to purchase a new phone from SK, it isn’t possible to just transfer my sim from the old phone to the new one.  

The good news is that SK Telecom and KTF announced early this year that sim locks and phone locks would be disabled within their respective companies in the first half of 2008. Before the year ends we can expect to be able to swap SK Telecom sim cards and KTF cards, meaning no more SK or KTF specific phones.

Why am I so excited about all these developments, because I prefer PDA phones and smart phones of which I have little to choose from in South Korea, also because majority of mobile phone dealers are not keen on doing business with foreigners. When the time comes that all locks are removed then I can theoretically plug in an SK or KTF sim into a 3G Nokia, 3G Palm Treo or the much anticipated 3G iPhone which is rumored to be announced in the WWDC (Worldwide Developers Conference) this Monday. The removal of all the locks also opens up the possibility of having a pre-paid sim just like other countries. I’m sure that most expats and tourists will love to be able to use their own cell phones by buying a prepaid sim at the airport.

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Posted in Seoul | 38 Comments »

38 Responses to “Korean Mobile Phones 101”

  1. By charro on Jul 1, 2008 | Reply

    Hey I read ur blog. Can you tell me-right this moment is it possible to buy a ISM card in Korea if I have an Unlocked phone. I bought an unlocked phone before I left the US and am now in Korea-but dont know where to get a SIM card.

    Thanks I will appreciate your advice.


  2. By Terence on Jul 1, 2008 | Reply

    Thanks for your most informative blog! I am planning a trip to South Korea, so this info is very handy. Like the previous person (Charro), I’d like to know how I can buy a pre-paid local SIM card once I reach Seoul. Can I buy it at the airport? Thanks.

  3. By admin on Jul 1, 2008 | Reply

    @ Charro, Terrence. I checked with my colleague at work and I’m quite certain that Prepaid SIM cards are not available in Korea.

    I believe it is possible to rent a phone from either KT, SK Telecom or LG at the airport.

  4. By richard on Sep 29, 2008 | Reply

    i am currently working here in korea and wanting to own an iphone 3g and use it here. if i may ask sir, is the network offered by show ktf with 3g compatible with iphone 3gs umts/hsdpa? iphone 3g offers dual mode system which is the gsm/edge and umts/hsdpa if i am right. i am currently using an lg cyon phone under show ktfs’ wcdma/umts. if it’s possible to have my sim-lock removed -as you have mentioned above, then i will be able to use it on an unlock iphone 3g. i’m not really well informed with systems and networks sir and i will really appreciate your response. thanks in advance.

  5. By admin on Oct 2, 2008 | Reply

    @ Richard, KTF and SKT networks are both 3G (UMTS) capable and so is the iPhone 3G. Technically the iPhone will work in S. Korea, my friend from Singapore recently came for a holiday and he was able to roam on KTF’s network.

    The problem is unlocking KTF’s sim card to work with the iPhone 3G, they claim to be unlocked but as far as my tests are concerned (borrowed an SKT sim and put it in my Nokia E61 3G) I have not been successful.

    If I were you… test the SIM in your KTF phone with a foreign 3G phone if you can. I’d like to hear back from you if you are successful in getting it to work.

  6. By Odunbyeol on Oct 27, 2008 | Reply


    I’m from catalonia and now studing a master program in seoul, i’ve been mad from arrival here at getting a great phone, but, as you pinted out, the sim locking card is being a pain in my ass… My question is, will be theoretically possible to buy a samsung omnia in barcelona, or any other place, and then ask samsung to create a LOCKED simcard for it?? I want to do this because i can t read korean, and even when this phone is available in korea, i’ll not be able to read it…

    And also, any news on the unlocked SIMS??


  7. By admin on Oct 27, 2008 | Reply

    @Odunbyeol, its not Samsung you should be talking to about creating a locked sim card rather your chosen provider namely SKT or KTF since the sim cards or UICC as its called here in Korea to activate the phone for you. Technically there is no reason the Omnia should not work on either KTF or SKT’s network. I would suggest going to SKT or KTF and inquire about what you want to do before you take the plunge. Bringing along a person who speaks Korean will also help a lot.

    I have no news on unlocked sims.

    Good luck

  8. By Odunbyeol on Oct 27, 2008 | Reply

    Thanks for your help!!

    Well, I really, really hope I can use the omnia in korea… I would happily buy it in korea, but the problem is that I can’t understand korean, so I would have to flash it from korean to english, and that’s not too safe. So I want to buy one in barcelona (or an american one, since it is cdma) and then try to made ktf or sk to help meuse it in korea… I have some friends here to help me, but I’m not sure… You know, I was so willing to buy the omnia originally that i even bought a cheap 2nd hand cellphone while the samsung omnia was coming…so you can imagine my frustration now (yes, i’m a technoholic)

    Thanks again for your help

  9. By ryi on Oct 30, 2008 | Reply


    I’m planning to purchase a SCH-550 in Seoul. However, if i were to bring this phone back to Singapore, is it still workable with a singapore SIM card? Thanks for your help!

  10. By evan on Nov 2, 2008 | Reply

    Hello. I have an iphone 3g and I would like to use it with SK or KT if possible… You mentioned that the RUIM itself has some kind of protection that only allows it to be used on the phone for that network? Do you know what this lock is? Does it have something to do with the IMEI of the phone?


  11. By admin on Nov 5, 2008 | Reply

    @Evan, my apologies for the late reply. Unfortunately SIM cards are still locked. I was with a friend recently at an SKT outlet and they said that SIM cards are locked to the network and will not work with any foreign 3G phone. Sucks I know… but that’s the way it is for now.

  12. By admin on Nov 5, 2008 | Reply

    @ryi, I don’t think its a good idea to buy a phone. For starters I believe it is more expensive here in Korea.

  13. By Dhiren on Nov 9, 2008 | Reply

    your excellent note from June, 1 suggests that unlocked 3g sims will soon be available in South Korea – do you know when that will be the case or where I could get one if already available?
    I am dying to be able to use my blackberry with a local korean sim card. any advice welcome.


  14. By admin on Nov 10, 2008 | Reply

    @Dhiren, unfortunately the 3G sims are still locked. No word from SKT or KTF when they will be unlocked.

  15. By Dhiren on Nov 10, 2008 | Reply

    thanks for the prompt response. would be grateful if you would put a note when (or if) you learn that this happens.

  16. By joel on Mar 15, 2009 | Reply

    I have a phone I got in korea in 2005 a VK Mobile VK300c , I want to use it here in the US but am haveing trouble unlocking it .. I cant find a IMEI number for it . Can anyone help me ?

  17. By Daniel Hawkins on Mar 18, 2009 | Reply


    Thanks for the great post. I’ll be studying in Seoul in September of 2009. Do you happen to know if it will be possible to swap out the SIM card from an unlocked iPhone with a local prepaid SIM card?

    If yes, how would data plans work etc.? I would be fine only using WiFi on the iPhone for data, but I’m not really sure how data and regular calls would be handled by KTF.

  18. By admin on Mar 23, 2009 | Reply


    Unfortunately you will not be able to use your iPhone3G by swapping sims here in Korea. For some bizzare reason, Korean carriers lock their sims too, meaning the phones here are paired with the sims.

    To make things clearer, I can’t even swap local phones from the same carrier here. That might change soon, we’ll have to wait and see after April when they start loosening up the regulations.

    I have no info with regards to the data plans here but there are a lot of free and open wifi hotspots especially coffee shops in Korea.

  19. By admin on Mar 23, 2009 | Reply

    @Joel, sorry I’m not familiar with that phone.

  20. By vegemitekid on Mar 27, 2009 | Reply

    thanks so much for the great post!
    Do you know when in April they’ll loosen regulations? im in korea at the moment and would like to use my Nokia E71 from Australia with the KTF network.

    Also, do you know by any chance if it’s possible to get korean on this phone?

  21. By admin on Apr 2, 2009 | Reply

    @vegemite, unfortunately I do not have specific information on when WIPI will be abolished.

    AFAIK the Korean language is not supported on any current Nokia GSM / 3G phone. I would suggest checking with Nokia in Australia.

  22. By Stefan on Apr 3, 2009 | Reply

    iPhone does support Korean ;) .

  23. By Jhon on Apr 6, 2009 | Reply

    Hi..I’m Jhon .I live in seoul few month ago I buy the iPhone 3g but I don’t know how to get the ktf or skt line for local call Korea . My iPhone is unloked if I call 114 they say contrc to ktf or skt telecom .
    One quasen more can I get the nespot Internet line for iPhone 3g. And where the get inter net line.

  24. By admin on Apr 6, 2009 | Reply

    @Jhon, AFIK you won’t be able to get your iPhone 3G to work with the local sim cards from SKT or KTF. If you have a friend who’s got a local 3G phone, try popping his SIM (USIM) card into your iPhone and see if it works. Keep me posted.

    NESPOT is a WIFI service, personally I don’t recommend it as the coverage is spotty, besides most coffee shops (i.e. Tom n Tom, Seven Monkeys etc..) offer free WIFI. There are also a lot of open WIFI access points. If you must… then I would suggest visiting the Nespot homepage for info.

  25. By vegemitekid on Apr 20, 2009 | Reply

    Jhon, I have purchased a korean 3g phone and am now on the SK Telecom network. I tried putting my korean sim card in my unlocked Nokia 3G Australian phone and it still does not work (probably will be the same thing for you with your iphone) Sim cards are still locked.. *sigh*

  26. By Michele on Jun 1, 2009 | Reply


    I have a samsung anycall phone and I am leaving korea in august to go back home to canada. I called rodgers to ask them about using this phone in canada and the guy told me that as long as it’s not locked i can get a new sim card and it can work. I’m just wondering how do I know if the phone is unlocked? the guy told me that in rumors that most Asian phone are unlocked. Is this true? How do I get it unlocked? Or can I use this phone when I go home for good? Thanks!!1

  27. By admin on Jun 1, 2009 | Reply

    The information from the Rodgers guy told you is accurate, most phones in Asia are unlocked since you payed full price for it unlike in N. America where the cost of the phone is heavily subsidized by the carrier such as AT&T, Verizon etc….

    Your phone will work in Canada as long as it is a WCDMA phone, most of the time you can tell if its a WDCMA phone because it has a SIM card or USIM as its called here in Korea.

    I would also suggest dropping by your provider and just double checking that your phone is indeed unlocked. Hope that helps.

  28. By vas on Aug 4, 2009 | Reply

    my boyfriend just moved to korea and needs a phone to stay in touch with family, we assumed his phone from the uk would work there-but it doesnt,,,whats the best way for him-i dont think he has a bank account yet(if thats important) and its slightly urgent cuz he’s getting homesick

  29. By admin on Aug 6, 2009 | Reply

    @vas, The quickest way I would say is to jump on Skype, WIFI Skype phones are also available, this allows you to call people on Skype for free. You can also call mobile phones and landlines with the purchase of Skype credits.

  30. By bentigno on Sep 2, 2009 | Reply

    Hello! my best is in Seoul and don’t know where he can buy cheap cellphones (LG ou Samsung)using double sim! if u don’t know, i’ll be gratefull to forward me useful web addressses.

  31. By admin on Sep 2, 2009 | Reply

    @betigno, the best place would be to look at pre-owned (used) cell phones. Expect to pay at least USD300 for an entry level no frills phone. Sorry to say no double sim mobiles are available in Korea.

  32. By desperate on Sep 7, 2009 | Reply

    I’m so glad to have found your website after much Googling! Basically my phone is dead and I’ll be moving to Korea next year, so I’m looking into a phone that works in the rest of the world and will eventually be able to make the transition smoothly into Korea.

    Basically as I understand it, a phone that supports both 2G (for the rest of the world) and and 3G (for Korea) networks will probably work in Korea eventually, as long as it supports UMTS 800/1800/2100 Mhz bands? (not sure about these frequencies, most sites I’ve been to suggest 2100 is becoming a global 3G standard)

    So LET’S SAY I get a phone tomorrow with 2G bands that work in GSM networks. With 3G bands that work in Korea/other 3G networks (specifically which band should I be looking out for?). A phone that is UNLOCKED. By September 2010, will I be able to go to Korea, get a local number/SIM card and pop it into this phone, transforming it tadahhh into a de facto Korean phone?

    Am extremely desperate as I suspect this will be quite a significant purchase, so I need to do my research right… Thank you so much for your help!

  33. By desperate on Sep 7, 2009 | Reply

    Sorry, an additional question: if I can’t use a Korean SIM card on a foreign-purchased phone, can I get an unlocked phone in Korea that I can eventually use with local networks overseas? Thanks once again

  34. By admin on Sep 13, 2009 | Reply

    I have not verified this but AFAIK Korean mobile phones are unlocked

  35. By admin on Sep 13, 2009 | Reply

    Most 3G WCDMA / UMTS phones are compatible worldwide so no need to look for a particular band

  36. By Andrew on Feb 13, 2010 | Reply

    Hi, the only way to get your foreign phone working in Korea at the moment is to go to the radio research lab in Yongsan (for Seoul) and get your phone registered. BUT this will cost you around 330,000KWN(about 300 US dollars) and will take up to 30 days, which is ridiculous! Then after, you can take your phone to a service booth and get a plan for your phone. If you go to KTF or SK, they’ll tell you to go register your phone first. I’ll be in Korea this summer and I hope they’ll soon release unlocked sims.

  37. By Michael in Seoul on Feb 16, 2010 | Reply

    I have an I-phone 3GS that works in Seoul, and is fine in expensive roaming mode using my Australian sim card.

    Can I buy a pre-paid sim in Seoul, and plug it into my phone and use it during my stay?


  38. By Stefan on Mar 3, 2011 | Reply

    Now you can use your foreign phone, as long as it`s lock free and it`s already published in Korea without any certification. Don`t know if there is any prepaid service available in this case. Gonna keep you updated.


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