Can't set APN Type.

Hello to all.
With windows phone 8.1 you can't change the setting "APN type"( like default, supl ...).
I really need to change this setting. You know if you can somehow? (also by modifying the system registry).
I need to add the word "dun" at type APN. (default,supl,dun)


With windows phone 8.1 no longer works the application "access point". while with windows phone 8 was possible to change all the settings you want for the apn.

thanks for help.

sorry for bad english.