[cisco-voip] Dry Closure Phones

Jason Aarons (US) jason.aarons at us.didata.com
Tue Nov 23 19:39:48 EST 2010


David, from some Google searches it means no voltage,  I see this in electrical engineering in environments where dust might explode, like in a grain elevator, my electrical engineer buddy makes electrical control panels for devices that are based on vacuum, you have lots of hoses with air under the panel that lead back to somewhere safe.

Put a volt meter on it and it should read nothing.  Where are you going to find a phone without power, ringer, etc.

dry contact is that the contacts are floating. One example
is the COM, NC and NO contacts of the relays. If no voltage
is connected to them, it is called dry contacts.
Volt-free and dry contact mean the same thing. If a control
system supplier offers a dry contact for you to read as a
status bit, then he is offering to close a contact (relay
or contact output) that is nothing more that a stand-alone
set of contacts with no voltage, current, or anything else
impressed across the contact set. It becomes the user's
responsibility to determine how to sense that contact
closure. Usually you do this by putting a voltage on one
side and sensing the voltage on a return line from the
other side of the contact when it closes. Once you apply
voltage to the contacts, it becomes a wet contact.
You "wet" the contact with a sensible voltage level.


From: cisco-voip-bounces at puck.nether.net [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Eric Butcher
Sent: Tuesday, November 23, 2010 7:23 PM
To: David Zhars; Lelio Fulgenzi
Cc: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] Dry Closure Phones

I think the term dry, in this case, means no voltage is supplied.


Eric Butcher
Cisco Unified Communications Engineer
CDW Professional Services
11711 N Meridian, Ste 225
Carmel, IN  46032
* 317.569.4282 - IP Phone
* 765.744.1458 - Mobile
* eric.butcher at cdw.com<mailto:eric.butcher at cdw.com>
http://www.cdw.com/


From: David Zhars [mailto:dzhars at gmail.com]
Sent: Tuesday, November 23, 2010 3:24 PM
To: Lelio Fulgenzi
Cc: Eric Butcher; cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] Dry Closure Phones

Yes apparently in the Dispatch center, the phones and radio traffic is recorded.  Apparently (that word again) the PC needs a "dry closure connection" so the user won't hear both phone and radio at the same time.  This may not be doable with what I am seeing, although the TAM stuff might be a possibility.  I know the older analog phones definitely had this dry closure stuff.  I will keep exploring!  Thanks everyone for the feedback.
On Tue, Nov 23, 2010 at 1:08 PM, Lelio Fulgenzi <lelio at uoguelph.ca<mailto:lelio at uoguelph.ca>> wrote:
Yes, it looks like it has the more common telco style stipped end and screw type connectors. That's cool.


---
Lelio Fulgenzi, B.A.
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Cooking with unix is easy. You just sed it and forget it.
                              - LFJ (with apologies to Mr. Popeil)
________________________________
From: "Eric Butcher" <Eric.Butcher at cdw.com<mailto:Eric.Butcher at cdw.com>>
To: "Lelio Fulgenzi" <lelio at uoguelph.ca<mailto:lelio at uoguelph.ca>>
Cc: "David Zhars" <dzhars at gmail.com<mailto:dzhars at gmail.com>>, cisco-voip at puck.nether.net<mailto:cisco-voip at puck.nether.net>
Sent: Tuesday, November 23, 2010 2:06:23 PM
Subject: RE: [cisco-voip] Dry Closure Phones

Great!  I didn't know they came out with a new one!  The original had 66 style punchdowns for the wires.  This one looks to use more convenient methods.  Looks like you still have to make your own power wire though :)


Eric Butcher
Cisco Unified Communications Engineer
CDW Professional Services
11711 N Meridian, Ste 225
Carmel, IN  46032
* 317.569.4282 - IP Phone
* 765.744.1458 - Mobile
* eric.butcher at cdw.com<mailto:eric.butcher at cdw.com>
http://www.cdw.com/


From: Lelio Fulgenzi [mailto:lelio at uoguelph.ca<mailto:lelio at uoguelph.ca>]
Sent: Tuesday, November 23, 2010 1:58 PM
To: Eric Butcher
Cc: David Zhars; cisco-voip at puck.nether.net<mailto:cisco-voip at puck.nether.net>
Subject: Re: [cisco-voip] Dry Closure Phones

...and it looks like the TAM-B has been updated to the TAMB2!

http://www.bogen.com/products/telephonepaging/



---
Lelio Fulgenzi, B.A.
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Cooking with unix is easy. You just sed it and forget it.
                              - LFJ (with apologies to Mr. Popeil)
________________________________
From: "Eric Butcher" <Eric.Butcher at cdw.com<mailto:Eric.Butcher at cdw.com>>
To: "David Zhars" <dzhars at gmail.com<mailto:dzhars at gmail.com>>, cisco-voip at puck.nether.net<mailto:cisco-voip at puck.nether.net>
Sent: Tuesday, November 23, 2010 1:42:18 PM
Subject: Re: [cisco-voip] Dry Closure Phones
With contact closure, you use a pair of wires to create a loop to signal a channel open, and a separate pair of wires to carry the audio (traditional tip and ring pair).  You cannot do this without an adaptor.  The best way I have found is to use a bogen tam-b or a pagepal, connected to an FXO port.


Eric Butcher
Cisco Unified Communications Engineer
CDW Professional Services
11711 N Meridian, Ste 225
Carmel, IN  46032
* 317.569.4282 - IP Phone
* 765.744.1458 - Mobile
* eric.butcher at cdw.com<mailto:eric.butcher at cdw.com>
http://www.cdw.com/


From: cisco-voip-bounces at puck.nether.net<mailto:cisco-voip-bounces at puck.nether.net> [mailto:cisco-voip-bounces at puck.nether.net<mailto:cisco-voip-bounces at puck.nether.net>] On Behalf Of David Zhars
Sent: Tuesday, November 23, 2010 1:11 PM
To: cisco-voip at puck.nether.net<mailto:cisco-voip at puck.nether.net>
Subject: [cisco-voip] Dry Closure Phones

An app we are installing at our Police Dept requires the phones to have a "dry closure" contact or something like that.
If I google this, I see a Dry Closure thing for 2600/3600 series, so I am researching that.
Do any phones supported by CCM 8 support dry closure?  Ultimately, I want the phones to work with SRST, so I probably don't want to stray too far from the Cisco wagon...

Appreciate any insight.

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