This (dialback always on same port) is true only for "shell" users, i.e.
Service-Type = Callback-Login-User in Radius 2.0 terms. For a PPP etc
user, i.e. Callback-Framed-User, you must use a location in the PM, and
there you can set a "dial group" restricting the chosen dialout port to
be one of those that have the same "dial group" set. I filed an RFE for
the ability to set a "dial group" for Callback-Login-User too a couple
of years ago, but it hasn't been implemented.
--Per Hedeland
per@erix.ericsson.se