Using sub-brand carriers
https://www.egmobile.co.kr
If your smartphone contract ended, why don't you move to one of sub-brand carriers? I'm using a sub-brand carrier.
I was originally using SK Telecom, but after the smartphone contract ended, I moved to EG Mobile, a reseller of KT network. I'm using EG Smart 70 that provide me 200 minutes of voice, 300 MB of data, 100 messages are provided as a standard service.
The picture below shows that I've paid for my phone bill for recent six months.
If you pay unnecessarily much money for the phone bill you can move to a sub-brand carrier and save some money. I recommend you to buy stocks with the saved money :)
In addition to Easy Mobile, there are many cheap sub-brand carriers such as Annextelecom.
Annextelecom - https://www.annextele.com
Hellowmobile - http://www.cjhello.com
Snowman - http://www.snowman.co.kr
Mmobile - https://www.ktmmobile.com
Freemobile - http://www.freet.co.kr
https://100mstocks.blogspot.kr/2017/09/using-sub-brand-carriers.html