dtmf

voice → application

Report a DTMF key after the remote caller releases it.

Data

Field	Type	Presence	Constraints	Description
seq	integer	required	≥ 0	Monotonic event sequence number within the session.
pressed_at	integer	required	≥ 0	Epoch timestamp in milliseconds when the key was pressed.
released_at	integer	required	≥ 0	Epoch timestamp in milliseconds when the key was released.
digit	string	required	length ≥ 1	DTMF digit that was pressed.

Cross-field constraints: pressed_at ≤ released_at.

Example: canonical

{
  "seq": 7,
  "pressed_at": 1700000000000,
  "released_at": 1700000000120,
  "digit": "5"
}