I spent a few hours tonight figuring this out, and it looks like there's some new settings to be added to the carrier.plist file. With multiple APN's now likely for on-device data, voicemail, MMS, and tethering, it looks like Apple is giving carriers more fine-grained control over how users are able to set APN settings.

AllowEDGEEditing is still required to enable the "Cellular Data Network" section, and the following values enable what you can edit from there.

Adding a Boolean value for IsMMSUserEditable set to true will allow editing of MMS settings through the menu.



To be able to edit APN's, each APN dictionary mush have a new IsAPNUserEditable boolean value set to true. Additionally, a label string value should be added to each APN item, although at this time, it does not appear to be displayed or used in the settings menu, there appears to be a bug with the 3rd APN if it is not. Even with label set, the APN, Username, and Password for the 3rd APN (if used) is not shown. Also note the propper format for MMS settings.



For each APN, you'll also see settings for MMS, Tethering Traffic, and Tethering Auth. If you're getting crashes trying to get to this screen, it is most likely because you are using incorrect negative type-mask settings. Refer to this thread for the correct settings, and note that it now appears there is a 5th bit used for "Tethering Auth", which I'm not entirely sure of the purpose right now.