[VoIP] WE 2500 question
Steph Kerman
stfkerman at jps.net
Wed Mar 14 15:45:37 CST 2007
I'm not surprised though. It's unlikely that a loop interface that can
drive an electronic phone would not be capable of driving a 2500 set. A
conventional 2500 set with L-C dial is specified to work down to 23mA
and doesn't quit abruptly until the current is substantially below that,
although the tones may be out of spec. Passive telephones like this
will draw loop current at much lower applied voltages than most
electronic telephones. The dial uses a germanium transistor which can
also work at very low voltage.
Electronic telephones contain a rectifier bridge to assure proper
polarity at the speech network IC and use speech network ICs having
higher conduction threshholds than most any passive phone These two
factors together generally mean that electronic phones require a higher
applied voltage than a 2500 set.
Steph
Jayson Smith wrote:
> Hello,
> The polarity reversal idea worked! I didn't seriously think it would. I'd
> pretty much decided that my IAXy wasn't providing enough power. But doing
> what Steph suggested fixed the problem! Thanks everybody!
> Jayson.
>
> ----- Original Message -----
> From: "Steph Kerman" <stfkerman at jps.net>
> To: "Voice Over IP Tandem for Analog Switches" <voip at ckts.info>
> Cc: "Jayson Smith" <ratguy at bellsouth.net>
> Sent: Wednesday, March 14, 2007 4:42 PM
> Subject: Re: [VoIP] WE 2500 question
>
>
>
>> Fine.
>>
>> First let's define terms. A plug is a male connector attached to the
>> end of a cord. A jack is a female connector, usually mounted stationary
>> mounted to a surface or in a piece of equipment
>>
>> Standard double plug-ended modular cords inherently reverse the polarity
>> of the line. This is because they are flat, have a ridge along one
>> face, and the plugs are installed with the latching key on the same side
>> as the ridge. This reversal is normally compensated by the fact that
>> the wall jack and jack in the base of the phone are different, with
>> oppositely color coded contacts. Because of this inherent reversal, if
>> you connect a standard flat line cord between 2 wall jacks or 2
>> telephone set base jacks you will find continuity between red at one end
>> and green at the other, rather than between identical colors as you
>> probably would expect.
>>
>> For this reason, if you plug your phone into one jack of the "T" and use
>> a second line cord to patch the second jack of the "T" to the wall, this
>> will reverse the polarity fed to the phone. The male end of the "T"
>> which normally would be inserted in a wall jack is unused when using a
>> "T" to reverse polarity this way.
>>
>> Steph
>>
>> Jayson Smith wrote:
>>
>>> Hi,
>>> Yes, we've got lots of those. We usually get them at Radio Shack.
>>>
> They've
>
>>> got them now with two, three, four, or maybe even more jacks. I think I
>>>
> have
>
>>> both the type that is an adaptor block, and also the type that has the
>>>
> phone
>
>>> jacks at the other end of a long phone cord, thus my "extension"
>>>
> reference.
>
>>> Jayson.
>>>
>>> ----- Original Message -----
>>> From: "Steph Kerman" <stfkerman at jps.net>
>>> To: "Voice Over IP Tandem for Analog Switches" <voip at ckts.info>
>>> Cc: "Jayson Smith" <ratguy at bellsouth.net>
>>> Sent: Wednesday, March 14, 2007 4:27 PM
>>> Subject: Re: [VoIP] WE 2500 question
>>>
>>>
>>>
>>>
>>>> There is a widely available adapter that you plug into an existing jack
>>>> and which has 2 jacks on the back into which 2 devices can be plugged
>>>> instead of the single device that could have been plugged into the
>>>> original jack. Most people call it a "T" or "tee". Do you have one?
>>>> "duplex/extension" means anything and nothing to me.
>>>>
>>>> Steph
>>>>
>>>> Jayson Smith wrote:
>>>>
>>>>
>>>>> Hi,
>>>>> Do you mean, like a duplex/extension/whatever you call those? The
>>>>>
> phone
>
>>> does
>>>
>>>
>>>>> have a modular jack.
>>>>> Jayson.
>>>>>
>>>>> ----- Original Message -----
>>>>> From: "Steph Kerman" <stfkerman at jps.net>
>>>>> To: "Jayson Smith" <ratguy at bellsouth.net>; "Voice Over IP Tandem for
>>>>>
>>>>>
>>> Analog
>>>
>>>
>>>>> Switches" <voip at ckts.info>
>>>>> Sent: Wednesday, March 14, 2007 4:18 PM
>>>>> Subject: Re: [VoIP] WE 2500 question
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> Does the phone have a modular plug?
>>>>>>
>>>>>> Do you have a modular "T" for connecting 2 phones to the same jack?
>>>>>>
>>>>>> Steph
>>>>>>
>>>>>> Jayson Smith wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>> Hi,
>>>>>>> Unfortunately, being blind, I'm not in a good position to measure
>>>>>>>
>>>>>>>
>>> those
>>>
>>>
>>>>>>> voltages. I just tried several phone cords, including the one
>>>>>>>
> shipped
>
>>>>>>>
>>>>> with
>>>>>
>>>>>
>>>>>
>>>>>>> the phone, on my unused BPA-410. None worked. I like the phone, it's
>>>>>>>
>>>>>>>
>>>>>>>
>>>>> exactly
>>>>>
>>>>>
>>>>>
>>>>>>> what I wanted, I just wish it'd work on my IAXy!
>>>>>>> Jayson.
>>>>>>>
>>>>>>> ----- Original Message -----
>>>>>>> From: "Martin Harriss" <martin at Princeton.EDU>
>>>>>>> To: "Jayson Smith" <ratguy at bellsouth.net>; "Voice Over IP Tandem for
>>>>>>>
>>>>>>>
>>>>>>>
>>>>> Analog
>>>>>
>>>>>
>>>>>
>>>>>>> Switches" <voip at ckts.info>
>>>>>>> Sent: Wednesday, March 14, 2007 3:05 PM
>>>>>>> Subject: Re: [VoIP] WE 2500 question
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> Jayson Smith wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> Hello,
>>>>>>>>> So is this saying, I'd need to somehow get a phone cord with some
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>> wires
>>>>>
>>>>>
>>>>>
>>>>>>>>> reversed? I'll try the phone cord that came with the thing. For
>>>>>>>>>
>>>>>>>>>
>>> those
>>>
>>>
>>>>>>>>> curious people among you, here's a recording of what I'm getting.
>>>>>>>>> http://www.bluegrasspals.com/2500.wav
>>>>>>>>> Jayson.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>> Jayson,
>>>>>>>>
>>>>>>>> Are you in a position to measure the off-hook and on-hook voltage
>>>>>>>>
> for
>
>>>>>>>> this phone/ATA combination? (Or have someone else do it for you?)
>>>>>>>>
>>>>>>>>
>>> It
>>>
>>>
>>>>>>>> would also be interesting to measure the off-hook voltage both with
>>>>>>>>
>>>>>>>>
>>> and
>>>
>>>
>>>>>>>> without one of the dial keys pressed. I wonder if the ATA is
>>>>>>>>
> putting
>
>>>>>>>> out enough voltage (especially when the phone is off-hook) to run
>>>>>>>>
> the
>
>>>>>>>> dial pad.
>>>>>>>>
>>>>>>>> I seem to recall that when you pressed a key on those old dial pads
>>>>>>>>
>>>>>>>>
>>> the
>>>
>>>
>>>>>>>> switch contacts somehow generated an electronic "kick" (for want of
>>>>>>>>
> a
>
>>>>>>>> better word) to start the oscillator, which then kept going of its
>>>>>>>>
>>>>>>>>
>>> own
>>>
>>>
>>>>>>>> accord. I wonder if what you are hearing is this "kick" starting
>>>>>>>>
> the
>
>>>>>>>> oscillator for a few cycles, but then the line voltage is not
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>> sufficient
>>>>>
>>>>>
>>>>>
>>>>>>>> to keep the oscillator running.
>>>>>>>>
>>>>>>>> Martin
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> VoIP mailing list
>>>>>>> VoIP at ckts.info
>>>>>>> http://lists.ckts.info/mailman/listinfo/voip
>>>>>>> Project Web Page: http://www.ckts.info/
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>> _______________________________________________
>>>>> VoIP mailing list
>>>>> VoIP at ckts.info
>>>>> http://lists.ckts.info/mailman/listinfo/voip
>>>>> Project Web Page: http://www.ckts.info/
>>>>>
>>>>>
>>>>>
>>>>>
>>> _______________________________________________
>>> VoIP mailing list
>>> VoIP at ckts.info
>>> http://lists.ckts.info/mailman/listinfo/voip
>>> Project Web Page: http://www.ckts.info/
>>>
>>>
>>>
>
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>
>
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