Subject: From: Date:

Re: [ECS] Local Phone Sessions joerut.epix.net Fri, 28 Jan 2000 19:51:41 -0500

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LEC1964@aol.com wrote:
> 
> 
Thanks Larry that seems to be exactly what I need with the added bonus
of leaving messages VIA the local phone. I actually was thinking of
something similar but it was a bit more HARDWARE complicated. 

One last question. Did you build or purchase your touch tone decoder?

Thanks Again
Joe Rut



Joe,
>      This might be of some help after upgrading to Windows and the inherent
> loss of the Bigmouth phone interface. The Bigmouth card along with a number
> of other devices that use in-house phones all have one thing in common. They
> replace the phone companys "talk power" with one that they provide. Talk
> power is the DC component of the phone companys service. Without going into
> more detail, phones actually only have 7.5-8.5 volts DC when they are "off
> hook". This voltage creates about 30 to 40 milliamps of current. By replacing
> the phone companys pair with a pair from an equivalent local voltage/current
> source a phone will become fully functional for both voice and DTMF tone
> (Touchtone) transmission/reception.
>      This is can be done with a relay. Using a DPDT relay the center or
> movable contacts should be wired to the phones to be used for the local
> sessions which also includes the modem. The normally closed when
> de-energized, non-movable, contacts  should be wired to the phone company.
> The non-movable contacts that "make" on energization of the relay coil should
> be wired to a local power source. This local power source could be as simple
> as a plug-in 12 volt DC  transformer using appropriate current limiting
> resistors. Polarity must be observed. Normally the color code used for the
> phone wiring for line 1 is red and green. Red is negative. Green is positive.
>      When a local power source, at least one phone, and a modem are all
> connected a local/remote phone session is possible. If Phone-Interface-C is
> set to "answer" ECS thinks it's answering a remote phone call but of course
> it's not. In fact, you will first have the opportunity to even leave a
> message. Some ECS users have indicated that they leave phone messages for
> other household members and this is an extra benefit that is available with a
> remote phone session. A touchtone entry # will start the interactive session.
>      There are several methods that can used to energize the phone transfer
> relay and to notify ECS that a phone session should commence. A PLC (X-10)
> pushbutton command could be used to notify ECS. A touchtone decoder could
> also be used.
>      I have to admit that I don't use local phone sessions but I was curious
> to see if it was possible and how efficient this method of interactive
> control really is. Since there is a "home run" of my phone service to my
> security panel and also 12 volts DC available at that location (security
> backup battery) I placed the transfer relay there. It took less than an hour
> to do the wiring and since I had a relay there was no cost. Two 68 ohm
> resistors (one in each conductor) limit the current to about 35 milliamps. I
> use a programmable four output touchtone decoder to notify ECS. The decoder
> uses a standard modular telephone connector and has screw connectors for its
> four relay outputs.
>       Picking up any phone in the house will initially provide standard phone
> service and access to the phone companys "switched network". However, if any
> one of the four unique two button touchtone codes are entered, a relay
> contact on the decoder will close and ECS is notified via a Micro Redac
> digital input. ECS will then respond by using a Micro Redac relay output to
> control and energize the phone transfer relay. A programmed delay is used to
> provide adequate time for "line settling" prior to Phone-Interface-C going to
> "answer".
>      In summary I would have to say that this does work reasonably well.
> However  these would be my recommendations. (1) Use a single cordless phone
> and one or two standard phones to minimize the wiring. (2) Wall transformers
> tend to be poorly filtered with no regulation and will produce audible
> background hum. Use a better quality DC power supply. I purchased a quality
> supply for about $25 for use with local SR phone sessions which by the way
> requires the same transfer scheme. (3) I would use phone session macros.
> Since I use abbreviations in Group, Event, and Item descriptions it was hard
> to understand the TTS audio.
>      I hope this will help and I apologize for my rambling text.
> 
> Larry C.

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