Call conference not working on my S2, issues with long sms

---

I got a Galaxy S2 from Korea, and currently in India, initially I had this problem of not being able to send messages, while I can receive them and I had to change some device setting and that works, partially.
Recently I tried to conference calls on my phone and I don't see a merge/conference option in any form or setting. I called my operator to make sure they have not disabled it and confirmed it to me enabled. Any thoughts suggestions would be great!

a second issue is wrt sending sms, while I had to change sms prefs to CS (Circuit Switched) from PS (Packet Switched), I cannot send longer sms, it converts them automatically to MMS and just displays that its sending constantly and nothing more happens .

I am using the default ICS Stock ROM provided by Samsung Korean variant.

PS: I would love to know the hardware differences between the international version and the korean version, I seem to have NFC while the others did not seem to have, These possible driver mismatch is a concern to flash any ROMs.

Thanks,
Rv.