3.1.3 Initialization

The caller MUST initialize the CBCP protocol if either the caller or the answerer has successfully negotiated for operation 0x06 of the LCP configuration option 0x0D during the LCP protocol negotiation. The negotiation of LCP options is defined in [RFC1661]. The LCP Callback configuration option 0xOD is defined as LCP Extension in [RFC1570] section 2.3. The operation 0x06 as defined in [IANAPPPNUM] MUST be used to specify the usage of CBCP to negotiate callback settings. The message syntax of the LCP Callback configuration option with the operation 0x06 is defined in section 2.2.1.

The CBCP MUST be initialized only after the Authentication Phase is complete. The Current State of the state machine will be set to CBCP_STATE_WAIT_FOR_REQUEST. The Caller-specified Phone Number will be initialized with the valid phone number the caller wants to receive the callback on. If this is not set, the caller MUST NOT use "Callback to a user-specifiable number" as the Callback type from the supported callback options provided by the answerer. The Caller-specifiedCallback Delay will be initialized to a valid delay that the caller wants to report to the answerer as a part of the Callback Response message.