To have customized behaviors when dialog reset/submit, please implement your version of openDialog in call.js. Which avoids panel specific logic placed in settings.js. You can do that by:
1. Removing `data-href="#carrier-mmsSettings"` from the mms settings button so that the default `openDialog` will not be triggered by default.
2. Add a click event handler on the button and do your customized things in the handler. Call to `openDialog` in the end of the handler.

You can refer to `openWifiSettingDialog` in `hotsopt.js` for implementation details.