allmost same problem over here (using hi (=kpn))all the symptoms except for the mms one..and Im not sure if its only after a voice call...apart from not being able to use data connection you might allso find you are unreachable by phone like me..Have you had this too?I have not found a solution other than flight mode/reset and dont think kpn helpdesk is capable..hope you will find a solution and w