When Telephone is selected from the main menu, the graphics stage (GT) 0x3b sends to broadcast high 0xff the command:
# Select Telephone from Main Menu
3B 05 FF 20 02 0C EF
I'd hazard a guess that the MID would send the same- perhaps even with button states, i.e. press, hold, release, as I believe there's a dedicated button.
It's important to note that the same command is sent when Top 8 is selected from within the Telephone submenu.
This isn't an issue on the MID and MK1, MK2, and MK3 <= 3-1/31, as Top 8 is the default Telephone home screen. Whether you select Telephone from the main menu, or Top 8 from the Telephone submenu, the result is the same. Everyone is happy.
However, following the UI update, the MK3 (<= 3-1/40) and MK4 would open the Dial interface which was redesigned to double as Telephone home screen. Bye bye stateless commands...
The telephone emulation will just need to maintain a session state as to be able to differentiate between opening Telephone from the main menu, vs. opening Top 8 from the Telephone submenu. Not the end of the world, but required if emulating existing behaviour.