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

[Joe Greco]

> 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.

That is, to say, they're not willing to go to the extensive amount of
trouble to do so.

> 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.  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).

Your best bet may be something like this:

http://www.3com.com/products/en_US/detail.jsp?tab=features&pathtype=purchase&sku=WEBBNCNJ220SYS

I'm guessing that the uplink can be set to 10/full.  You ought to be able
to dump a bunch of these into a PoE switch with ports locked at 10/full.
You might even find that you can run some runs at 100/full, but don't bet
anything on it.

The 10/full is possible because there's no chance of collisions on a
switch-to-switch Ethernet, and essentially gives you up-to-2x-10Mbps-hub
performance.

This is a neat way to handle some of these sorts of problems.

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

What's all this about RS485?  10/100 Ethernet is two pair (unless you get
something stupid like 100VG).  You probably can't get the 100 on any 
reasonable run of Cat3, but by all means, run 10.  We've done it in the 
past over fairly long distances, thanks to full duplex you need not worry
about the collision domain issues.

Wireless might be an option but it's also a security nightmare.

... JG
-- 
Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
"We call it the 'one bite at the apple' rule. Give me one chance [and] then I
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