asterisk users - Nov 2004 - [OT] Old Building Needs a New Telephone System

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.  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).

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?

Ideas, anyone?

Thanks,
Mike

-- 
Michael Welter
Introspect Telephony Corp.
Denver, Colorado US
+1.303.674.2575
mike@introspect.com
www.introspect.com

> 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
won't contact you again." - Direct Marketing Ass'n position on
e-mail spam(CNN)
With 24 million small businesses in the US alone, that's way too many
apples.

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.

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.  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).
> 
> 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?
> 
> Ideas, anyone?
It is real easy. EoV (ethernet over vdsl).
I have done this and it works great.
For every 24 ports I used a 1u EoV, 1u splitter, 1u fxs gateway.
The little termination modems have ethernet and fxs.
Just add an * box, done.


-- 
Bob Knight
[-w] the work option
bk@minusw.com
925-449-9163

My standard answer to POE questions....Mostly stolen from or repeated in
a Network Computing issue about 2 months ago.


PoE factoids:

PoE uses the spare pairs *or* the data pairs (which one to use is
automatically detected) in an ethernet (10 or 10/100) cable to carry
-48V dc from the power sourcing equipment (PSE) in an endpoint switch
(or midspan hub) to the powered device (PD) appliance at the other end
of the cable. Clearly, use of the spare pairs requires that they be
connected all the way from PSE to PD, which may not be the case in some
legacy installations.

The PoE power limit is 13W per PSE port. A new standard is being
discussed which will raise this to about 25W. But don't expect it for a
few years and it's primary use is security cameras requiring
pan/tilt/zoom.

Newer ethernet switches include the PSE function internally, but Midspan
Hubs can also be used to insert PoE power in legacy installations.
Legacy PDs can also be powered by PoE 'splitters' or 'taps',
which pull
the power from the ethernet and deliver it to the PD via a short cable.

PoE appliances include:

	Phones
	Cameras
	RF ID readers
	Displays
	Wireless Access Points
	Musical instruments
	

The PoE standard is IEEE 802.3af. It was approved about a year ago.
There are previous, proprietary PoE schemes from a number of vendors.

PoE's -48 V dc is designated as Safety Extra-Low Voltage (SELV). SELV
(safety extra low voltage) is a secondary circuit which is designed and
protected so that under normal and single-fault conditions, the voltage
between any two accessible parts does not exceed a safe value (42.2 V
peak or 60 V DC). It is lower than standard telephone network voltage
(TNV).
> -----Original Message-----
> From: Kevin P. Fleming [mailto:kpfleming@starnetworks.us] 
> Sent: Monday, November 08, 2004 2:14 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] [OT] Old Building Needs a New 
> Telephone System
> 
> Tim Donahue wrote:
> > First, I will admit that I have not worked with PoE before so I'm 
> > asking this for my own benefit as well as the OP's benefit. 
>  Doesn't 
> > PoE require at lest 3 pairs to be availible?  I know that 
> pins 1, 2, 
> > 3, and
> > 6 get used for ethernet communications and doesn't the power get 
> > transmitted over pins 4 and 5?
> 
> A PoE-enabled connection needs all four pairs. Two pairs for 
> Tx/Rx, one pair for power, one pair for ground.
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