APN type
This specifies what types of data connection should use this set of APN settings. This is the second most important setting after the APN field itself.
If your carrier allows all data (including MMS, if you use it) to use the same APN settings, then this field may contain the special value of "*" (an asterisk). Note: the actual setting should not include the quotation marks.
Otherwise, if your carrier requires different APN settings for MMS and for internet data, you will need two different sets of APN settings, each with a different value in this field. This field determines which APN settings should be used for which types of communication.