[Asterisk-Users] [OT] Old Building Needs a New Telephone System

[Henry Devito]

I know I am top posting and that is a no no, but I would like to comment on
this generally. I just did this with a historic building with the same
situation cat3 two pair in each office.  I used a Tut systems solution
called expresso this gave us cable TV and Ethernet to each office over the
existing cat 3.  Amazing technology I think.  I'm not affiliated with them
at all.  I think their website is http://www.tutsystems.com
 

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Nick Bachmann
Sent: Friday, November 05, 2004 11:01 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] [OT] Old Building Needs a New Telephone System

Michael Welter wrote:

> We have a 100 year old building here in Colorado that needs a new 
> telephone system. The building (five floors) is steel frame with lath 
> and plaster walls. There is no crawl space above the ceilings or under 
> the floors.  The building is "historic", and nothing can be done to 
> the exterior.
>
> The current system uses existing Cat3 (two pair) to get to the digital 
> telephone set in each office.  Some offices have an additional pair 
> which is used for fax (and DSL).  I belive this fax line is a POTS 
> line from the telco.
>
> The owners would like to replace the existing telephone system, but 
> they are adamant that the exsiting wiring be reused.  


How about ADSI phones?  You can use the Cat 3 and still have fancy phones.

> They would like to provide a LAN connection to each office for both 
> data and voice.  (They would also like to install cable TV in each 
> office, but cable install costs would be $80,000+.)
>
> The owners are concerned about frequent power failures and keeping the 
> telephones operational.  Whatever equipemnt and telephone sets we put 
> in the offices will have to be powered from a central UPS (PoE).


Most ADSI phones will still allow basic telephone use (you can make 
calls but no display or lights) when the power goes out.

> So how can I do this?  Can I use RS485 adapters to get ethernet to 
> each office via the two pair?  What kind of data rate can I get with 
> RS485, and would it be half- or full-duplex?  


This would be possible, but is the least desirable of any possible 
option, since you can't really hope for more than 10Mbps H-D, since 
you're dealing with fewer twists and, likely, inferior cable 
construction.  You may have better luck on longer runs, but remember, 
adequately cabled Cat-5 isn't designed to go over 100m.  Based on the 
old buildings that I've cabled, you rarely get a straight shot.

> Would wireless work in a steel building? Is there some other 
> technology that can be used?


Wireless would be a good choice, especially if the building has a steel 
skin.  Without ever seeing the building, my recommendation would be to 
put a good 3Com or similar (NOT LINKSYS) AP staggered through every 
floor (i.e. not directly above the lower floor's... shift for greater 
coverage area) connected to your wiring closet with fiber.  Since you'll 
only have 5 runs, this shouldn't cost too much.  Allied Telesyn* media 
converters will set you back =~$150/end, or you could (preferably) get 
fiber cards for a switch which cost about the same. 

If you still wanted to do a cable based networking, you could just run 
the fiber to a small switch on each floor and figure out how to 
discretely feed cable to each office, but I can almost guarantee the 
solution will come down to conduit, which is hard to make look good.  At 
least with wireless, you only have one cable per floor to add and you 
can figure out how to put your AP in a discrete place.

You do have other options, such as products like Tut's 
(http://www.tutsys.com/mtu/products/expressomdu/index.cfm), but I think 
you'll find them expensive and limited.

If you want more details on how I've done stuff like this, feel free to 
email me off-list.  I also do consulting work, if you're interested...

Nick

*I recommend this particular brand because I've used their converters in 
lots of applications (including 10+ mile building-to-building runs) 
without ever seeing one die.  And they're pretty cheap.
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