The Advanced Profile defines the following additional messages which are explained in detail in separate sections.
The following 4 additional message types MAY be used in the Advanced Profile.
The CHALLENGE message is used with certain Authentication Methods. During authenticated session establishment, a Router sends a challenge message.
{align="left"} [CHALLENGE, AuthMethod|string, Extra|dict]
The AUTHENTICATE message is used with certain Authentication Methods. A Client having received a challenge is expected to respond by sending a signature or token.
{align="left"} [AUTHENTICATE, Signature|string, Extra|dict]
The CANCEL message is used with the Call Canceling advanced feature. A Caller can cancel and issued call actively by sending a cancel message to the Dealer.
{align="left"} [CANCEL, CALL.Request|id, Options|dict]
The INTERRUPT message is used with the Call Canceling advanced feature. Upon receiving a cancel for a pending call, a Dealer will issue an interrupt to the Callee.
{align="left"} [INTERRUPT, INVOCATION.Request|id, Options|dict]
The following table list the message type code for the OPTIONAL messages defined in this part of the document and their direction between peer roles.
{align="left"}
| Cod | Message | Pub | Brk | Subs | Calr | Dealr | Callee |
|---|---|---|---|---|---|---|---|
| 4 | CHALLENGE |
Rx | Tx | Rx | Rx | Tx | Rx |
| 5 | AUTHENTICATE |
Tx | Rx | Tx | Tx | Rx | Tx |
| 49 | CANCEL |
Tx | Rx | ||||
| 69 | INTERRUPT |
Tx | Rx |
"Tx" ("Rx") means the message is sent (received) by a peer of the respective role.