Enumerations

Closed value sets referenced by stanza attributes (e.g. terminate reasons). Generated from spec/enums/.

Encryption payload (enc) types

id: enc-types
status: draft

Values for the type attribute of an node, which carries Signal-protocol ciphertext. In call signaling, the media/call key is delivered to each recipient device inside one or more nodes using the EXISTING Signal session between the two devices (X3DH for the initial handshake, Double Ratchet thereafter). The type distinguishes a message that also bootstraps a new Signal session (pkmsg, a PreKeySignalMessage) from one sent over an already-established session (msg, a normal SignalMessage). These two tokens are well established in WhatsApp message encryption; their reuse for call key delivery is the working assumption here, marked probable.

Value	Confidence	Description
pkmsg	probable	PreKeySignalMessage. Used when there is no established Signal session with the target device yet: it bundles the X3DH prekey handshake material so the recipient can build the session, then decrypts the wrapped call/media key. Expected the first time a device pair exchanges a call (or after a session reset).
msg	probable	Normal SignalMessage over an already-established Double Ratchet session. Used for call key delivery once a session with the target device exists, which is the common case for contacts that have previously messaged or called each other.

Call media types

id: media-types
status: draft

Media track types that can appear in a 1:1 call, used by media descriptors inside the offer (

Value	Confidence	Description
audio	probable	The mandatory audio track, present in every 1:1 call. Believed to use the Opus codec carried in SRTP; the offer's
video	probable	Optional video track. Present from the start for a video call or added mid-call via a toggle/upgrade. Codec is believed to be in the H.264/VP8 family; negotiation details in the

Call terminate reasons

id: terminate-reasons
status: draft

Candidate values for the reason attribute on a (and, where it shares the vocabulary, ) call stanza. The reason explains why a call ended or was not connected and drives both UI (missed call, declined, busy) and call-log/state on each device. WhatsApp multi-device complicates this: when one of a user's linked devices answers or declines, the OTHER devices receive a terminate with an "elsewhere" reason so they stop ringing. The set below is a hedged working list; some values are inferred from observed UI behaviour rather than confirmed wire strings, and the exact spelling (hyphen vs underscore) is uncertain.

Value	Confidence	Description
timeout	probable	The call rang without being answered until the ring timeout elapsed; surfaces as a missed call. The most commonly inferred terminate reason.
busy	probable	The callee is already on another call (or otherwise busy) and cannot take this one; surfaces to the caller as busy/engaged.
declined	probable	The callee actively declined/rejected the call. May overlap with the reason carried by a stanza rather than a server-originated .
accept_elsewhere	speculative	Sent to a user's other linked devices once one device has accepted the call, telling them to stop ringing. The exact wire token is unconfirmed.
reject_elsewhere	speculative	Sent to a user's other linked devices once one device has rejected/declined the call, telling them to stop ringing. Wire token unconfirmed.
connection_lost	speculative	The media/transport connection dropped (network loss, relay failure) and could not be recovered, ending an in-progress call.
retry	speculative	Signals that the call setup should be retried, e.g. after a transient routing or session-establishment failure. Whether this is a true terminate reason or a separate control value is unclear.
cancelled	speculative	The caller hung up/cancelled before the callee answered (the outgoing-side counterpart to timeout). Distinguishing cancelled from timeout on the wire is an open question.
unknown	unknown	Placeholder for a terminate whose reason is absent or not yet decoded. Not necessarily a literal wire value; used by tooling when the reason cannot be classified.

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