When you press Esc to bypass the Microsoft Callback feature, your connection is dropped.

This problem occurs because the Cisco Internetwork Operating System is configured to contact the authenticating server and drops the connection when the Callback feature is bypassed.

The problem was resolved in version 12.2(2)XB5 of the Cisco IOS. See reference CSCdx05704 in the "Resolved Caveats—Cisco IOS Release 12.2(2)XB5".