Firefox OS/Comms/Dialer/USSD-MMI

Gabriele is the best person to contact for issues here.

• Numbers that start with * or #
• Network replies with some carrier-specific information
  • ex: how much credit left, or data traffic left, enable/disable voicemail
• Can be transactions
  • Can get a reply, interact with the reply, etc
  • Very hacky
  • Designed for single-SIM
  • UI uses window.postMessage, makes testing difficult, uses setTimeouts
• Biggest issues: needs multi-SIM support, needs better testing
• Special function for sending telephony.sendMMI function
  • Should use normal telephony.dial function
• Hacks depending on the network
• Whitelist of codes reimplemented on CDMA (normally for GSM) even though it doesn't really have it (we simulate them)
  • Covered well by unit testing
• Biggest issues:
  • Needs multi-SIM support
  • Needs better testing
  • Replies can be mixed up
    • 1. You send a message
    • 2. Get an event reply on that connection
    • 3. System message (unrelated) triggered when you get a response
      • Juggling both is not easy
      • What we do: ignore the connection events
      • Only set an event handler for system events
      • In there we try to figure out if it was solicited or not