I'm giving up with the problem and asking You for help. I bought my device in Korea. I live in Poland and since I landed with new mobile in PL I cannot send MMS by stock app:/ My carrier is T-Mobile. I've already checked and set APN settings (for milion times!!) for Internet and MMS. I can receive MMS but cannot send I've installed GO SMS Pro and I was able to send MMS but after update I cannot send it anymore :/ I started to googling, reading, checking etc. I found featureset.xml in system/etc and also found some DB according to MMS and APNs in /data/data/com.android.providerstelephony (I don't remember exacly the path): mms.db , hiddenmms.db and telephony.db . In the databases I found some data according to APNs. Also I found some APNs info in etc dir in some xml files.
I will be very grateful for help in my issue.