Phones for Asterisk and single-pair old phone wiring?

Kenny Lussier klussier at gmail.com
Wed Sep 3 11:25:59 EDT 2008


On Wed, Sep 3, 2008 at 10:34 AM, Ben Scott <dragonhawk at gmail.com> wrote:
> 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.

You can use pretty much any kind of phone that you want, but most of
the proprietary phones aren't just 2-wire analog. They are usually an
ISDN hybrid. You would need to manually configure the buttons on the
phones. You could also create entries in the dial plan on the Asterisk
box to intercept certain key sequences to do whatever you want (i.e.
configure the voicemail button to dial *xxx (xxx=extension number) and
configure the dial plan to go to the mailbox).

> 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.

Any phone can be connected to an Asterisk box, but you will need FXO
cards in the system to plug them into. Usually they are 4 ports to a
card, but you can also get an FXO channel bank. What I have done in
the past is have all of the analog phones go into an FXO channel bank,
then use the T1 interface on the channel bank to go into a T1 card in
the asterisk server. The config on the asterisk card can get a little
messy, but it works.

>  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.

If what you are describing is each cube/office has one LAN and one
Phone jack, you could use VoIP phones that have either a pass-through
port or a switch. In that case, you can plug the phone into the LAN
jack, and plug the PC into the phone. It isn't an optimal solution,
but again, it does work. Most of the Cisco/Linksys (formerly Sipura
SPA-9xx) phones have this feature.

>  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.

What you are talking about is an FXO Channel bank like this:
http://www.voipsupply.com/product_info.php?products_id=921&searchid=864995
or these: http://www.voip-info.org/wiki/view/Asterisk+Channel+Bank

>  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.

No harm in asking. The nice thing about Asterisk is that you can
pretty much do anything with it :-)

HTH,
Kenny


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