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Posted By: [email protected] AT&T 2500 VIDEO PHONES - 02/16/16 01:47 AM
Not sure if this is the right forum, but I do have 2 of these 2500 Video phones working perfectly on 2 landlines, that are connected to a modular 1A2 panel. What would I have to do to directly connect these sets to each other so I could bypass CO lines? Never found any reference to using them in an 'intercom-like manner', which is essentially what I want- No CO lines involved, just the 2 sets dedicated to each other for voice and picture. Just wondering....
Posted By: EV607797 Re: AT&T 2500 VIDEO PHONES - 02/16/16 03:12 AM
Well, there are a few ways to do this. The easiest way would be to use a 401B manual intercom card in your 620 panel to mimic the talk battery of a CO line. You would then connect the tip and ring of each phone to the intercom card's T/R output from the panel. Of course, you wouldn't be dialing anything to connect them; they'd always be connected to each other via this parallel connection.

You could also put a pair of automatic tie line cards in your panel, but those are nearly impossible to find.

Lastly, you could purchase an automatic ringdown device, such as this one from Viking Electronics that would ring the other set whenever one goes off-hook. It is a stand-alone unit that won't need any slots or power from your panel:

VIKING DLE-200B
Posted By: [email protected] Re: AT&T 2500 VIDEO PHONES - 02/16/16 04:33 AM
Thanks Ed. Haven't tried this approach yet, it will certainly handle the voice. I wasn't sure if it would support the color picture transmission. Is the bandwidth on the intercom card similar to a CO line?
Posted By: EV607797 Re: AT&T 2500 VIDEO PHONES - 02/16/16 04:58 AM
Sort of. There really isn't a bandwidth issue since you're not dealing with any distance to speak of. These units were designed to connect via the public network via thousands of feet of 'Category Zero' cable, so I think that you'll be fine. Your units will essentially be connected directly together, using the intercom card as only a source for talk battery feed.
Posted By: [email protected] Re: AT&T 2500 VIDEO PHONES - 02/16/16 05:07 AM
Thanks Ed, guess I made it out to be more complicated then it was. I'll be trying this weekend and will post results.
Posted By: Silversam Re: AT&T 2500 VIDEO PHONES - 02/16/16 01:55 PM
I've got a SanBar 4415 auto ringdown card (standalone) if you're interested, but a 401 card, as Ed suggested should work (unless the phones - which I'm not familiar with - need -48V).


Sam
Posted By: [email protected] Re: AT&T 2500 VIDEO PHONES - 02/17/16 02:46 AM
I've got the same ringdown card and the WE 418A, 419A, and 401B KTUs. Should have success with at least one. I'll post my results.
Posted By: Silversam Re: AT&T 2500 VIDEO PHONES - 02/17/16 01:50 PM
Great, let us know.

Sam
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