2.2.4.2 Callback Response Message

The Callback Response message is sent by a caller to an answerer. This message contains a configuration option selected by the caller.

The message format is specified as follows.

0	1	2	3	4	5	6	7	8	9	1 0	1	2	3	4	5	6	7	8	9	2 0	1	2	3	4	5	6	7	8	9	3 0	1
Code								Identifier								Length
Data (variable)
...

Code (1 byte): This MUST be 0x02.

Identifier (1 byte): This MUST specify a value that assists in matching the Callback Request message to the corresponding Callback Response message and Callback Acknowledgment message. This value MUST be the same as the Identifier received in the Callback Request message to denote that the response being sent is a response to the specific Callback Request message.

Length (2 bytes): This MUST specify the length of the message, including the Code, Identifier, Length, and Data fields.

Data (variable): This contains the configuration option selected by the caller (section 2.2.3).

The Callback Configuration Options MUST be sent with the following settings.

Callback configuration option	Settings
No Callback	The Callback Delay and Callback Address fields MUST not be present.
Callback to a user-specified number	The Callback Delay field SHOULD be modified to specify the delay the caller requires before the callback is received. The Address Type field of the Callback Address MUST be set to 0x01, and the Address field MUST be set to a ASCII null-terminated PSTN or ISDN address.
Callback to a pre-specified or an administrator-specified number	Callback Delay field SHOULD be modified to specify the delay the caller requires before the callback is received. The Callback Address field MUST not be present.