Well, it is beyond of my knowledge. I had asked the same question to Ken Chang. He told me that ril is responsible for the connection of 'supl', 'data', and 'mms'. But mmsc, mmsproxy, mmsport is only used by MMS service. As to why I am going to use 'ril.data.apnSettings', this setting name is given by Ken Chang. I think we should loop him for the correct answer.