I decided to give a shot at taking on the challenge of buying a Korean carrier smart phone and seeing what would be the limitations and challenges faced when trying to use these phones as everyday phones outside Korea, and if there are any real solutions to overcome these.

The phone i got hold was Samsung SHV-E110S, the LTE variant of the Samsung Galaxy S2 with the Qualcom dual-core processor, and featuring a larger screen than the standard S2.  In addition a colleague of mine has been using the SHV-M250K, this phone is identical to the Galaxy S2 bar the existence of the digital TV antenna.

1. Phone firmware has to tendency to switch to EDGE more than you can like, as there is no option as you find on the international phones of being able to set if to use GSM only, or WCDMA preferred or WCDMA only.  However for this you can find a solution by using tools such as AnyCut or even Notification toggle and selecting the 4G option, which pops an Android internal setting page that allows you to set this setting.
2. No combined SMS messages when sending, and limited to 80 characters per SMS.  If you are lucky you will be able to send SMS messages but only limited to 80 characters since the phone has been set to support extended characters for the Korean language, hence 80 characters effectively is equivalent of 160 characters.  However you also don’t have what you take for granted of sending large messages over 80 characters as a combined message, the very moment you type a message over 80 characters it converts the message into a MMS message.   However some custom ROMs have solutions for this limitation.
3. Unable to send SMS message at all.  For some phones you may not be even able to send any SMS messages, the phone firmware will not take the override SMS gateway given.  Even using Go SMS Pro does not sort this out.
4. No conference call capability (aka Merge calls).  This was a problem my colleague found, and after reading many a forum it was apparent that you cannot do this on these phones! Though the “Add Call” option exists, once you make the second call the option to merge calls has been replaced by the feature “Record Call”.  In addition on a normal phone selecting “Add Call” allows you to go to the Contact menu, with the Korean phones you only have the list of recent callers to select from.
5. Lack of Gorilla glass on most of these phones means the glass has a tendency to be easily cracked. Finding replacement glasses for these phones can be extremely difficult and costly on eBay since these phones tend to have a different external case design to accommodate a larger screen area that the international variants.
6. Not possible to replace the firmware with international phone firmware in most cases, attempting to do so may result in bricking your phone, or having a phone with lots of stability issues.
7. OTA (Over the Air) updates of firmware is not possible, and you will have to resort to manual update using ODIN or using Custom ROMs. Custom ROMs are not as easy to find or matured as international ROMs since the volume of phones are much less, hence there is less community drive on these particular phones.
8. Just like the US carrier phones, the Korean phones also do not have no FM radio tuner, a feature that the Asian market users tend to use.
9. Some phones may not support all the WCDMA and HSPA bands that work in other Asian countries and feature a different technology that is particularly focused for Korea, making these phones perform very poorly in data support outside Korea
10. Features that we take for granted such as call diverting, etc is omitted on these custom firmwares
11. The LTE band is not compatible with Sri Lanka telcos.  Dialog, Mobitel use band 3 (LTE 1800) while these phones ate usually LTE 2600, 700.

Based on these using these phones on other markets such as what i tried in Sri Lanka was not convenient for everyday use as the limitation were on very practical and daily applications such as network signals, sending SMSs, making business calls, etc.

However if you want a phone for making calls (without wanting the conference feature), you want to browse, listen to music and watch videos, these phones are excellent as they have the following advantages

1. Tend to have larger than screen sizes than the global variants
2. The battery has a larger capacity and you also get a spare battery and external charger, a common bundle when phones are sold in Korea
3. You get the LTE antenna on these phones, which telco’s in Asia are now starting to trial out these faster networks, making these phones more future ready for blinding fast internet though these phones have an LTE modem and antenna, these most operate in LTE 800 or 2600 which is not compatible with most region.