Phones for Asterisk and single-pair old phone wiring?

[Ben Scott]

Hi all,

  Anyone know of any kind of enhanced telephone set that can be
connected to an Asterisk-based system using plain old telephone phone
wiring?

Enhanced telephone set = Something more than a plain old telephone
set.  Programmable buttons for hold, line selection, special features,
etc.  Option for an LCD.  Like the proprietary digital telephone sets
used with Avaya, Nortel, NEC, and other "key" and "PBX" premises
telephone systems.

Plain old telephone wiring = A single pair of copper wires, guaranteed
to conduct electricity and nothing more.  Not Category 3 compliant,
let alone Category 5.  Forget Ethernet for VoIP.

  I've got a building full of 50 year old telephone wiring, which
works fine for our Norstar system.  I'm looking at upgrading to a
VoIP-capable system, and would love to be able to switch to Asterisk.
But rewiring the building with 4-pair Cat 5 to support
Ethernet-connected, PoE-powered telephone sets is infeasible.  (And
there are a non-trivial number of phones without convenient existing
LAN jacks nearby.)  So whatever I go with has to have a way to support
old wiring.

  I'm looking at Nortel's BCM (basically a hybrid Norstar/VoIP box),
but it's expensive, doesn't do SIP, and Nortel is not overly customer
friendly.  I'd love to use something like Asterisk instead.

  I'm envisioning a semi-proprietary solution that uses Asterisk and
VoIP, but also offers equipment suitable for old wiring. Maybe some
kind of PCI line card, or Ethernet-connected expansion module, which
connects proprietary digital sets to the Asterisk architecture.

  Connecting plain old telephones to analog adapters isn't an
acceptable solution.  All the desk sets on old wiring would either (1)
loose features beyond making telephone calls, or (2) require hook
flash and dialing feature codes to do anything (too cumbersome for the
users).

  I suspect no such thing exists, but I figure I'd ask.

-- Ben