   >> conference calls?
   >It's not Clipper, it's any encryption system.  I've seen a number of
   >designs; they generally involve a multi-line cleartext bridge.

	   A 'multi-line cleartext bridge?"
			 ^^^^^^^^^
	   And just were would you put that bridge?  If it isn't at one of
   the receiptants location, forget encryption at all.  You have blown any
   security you thought you might have had. 

Most of the people using encrypted conference bridges these days are
military (or equivalent, like CIA and other embassy personnel),
so putting bridges on the recipient's location is normal -
it's in a vault on a military base or Ft. Meade, and the
secure phones are in sound-proof rooms with big locks on the doors
because they're talking about Classified Stuff (or Golf with Other Generals.)

That paradigm will change as we start using encrypted phones in our
offices or homes to carry on normal conversations about dinner plans
and stock purchases and meeting schedules and technical info
and the good batch of illegal frop that we got last weekend from Bob;
most people don't use sound-proof vaults, and may use bridges in their
PBX or from the local phone company (3-way calls) or Long Distance
or value-added phone company (e.g. Alliance conference bridges).

If Clipjack is mainly used for the radio portion of cellular phones,
the conferencing aspects don't change.  But there may be a market niche for
trusted conference-bridge providers, though I suppose the inquisitors
would try to get a blanket wiretap authorization for many bridges,
just in case a Bad Guy might use the service.