This Attribute indicates a dialing string to be used for callback.
It MAY be used in Access-Accept packets. It MAY be used in an
Access-Request packet as a hint to the server that a Callback
service is desired, but the server is not required to honor the
A summary of the Callback-Number Attribute format is shown below.
The fields are transmitted from left to right.
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
| Type | Length | String ...
19 for Callback-Number.
The String field is one or more octets. The actual format of the
information is site or application specific, and a robust
implementation SHOULD support the field as undistinguished octets.
The codification of the range of allowed usage of this field is
outside the scope of this specification.