Default [Q] Change phone carrier after upgrade S3 to 4.3

Hi Guys,
I cannot use CDMA tool to change my carrier. This was successful when my phone was running 4.1.2, but now, cdma tool complains of CPS_ERROR BAD_SPC _MODE when trying to change IMSI. Even QPST fails to read the phone.
Can someone point me in the right direction? All I need is to reprogram my phone to another carrier.