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Author Topic: Just How Did This Phone Work?  (Read 2811 times)

jack21

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Just How Did This Phone Work?
« on: May 08, 2012, 04:07:24 PM »

I visited a house in our village in a street where attenuations are around the 56db mark and sync rates around 3800kbps at 6db SNRM. This chap had said he'd got speeds of half that. The line wiring was very unusual; out of the older style master socket was a 2-way splitter, and a separate microfilter plugged into each splitter socket. Into one microfilter was an ADSL cable running to an Orange Netgear N ADSL modem/router, and into the other microfilter was an ADSL cable running  to a  RangeMax(?) 'brick' plugged into a  mains extension. Both were detectable via wifi, and the one he was connected to was the Orange Netgear, and was syncing at 2200kbps at 6db SNRM with an attenuation of 59.5db. The 'brick' modem had a phone plugged into a phone socket in its side, and the phone worked. He said the 'brick' had been in use prior to Orange supplying a new router when he complained to them about the low speeds.

I immediately removed the splitter, one microfilter and the 'brick', plugged his phone into the phone socket in the single microfilter from the master socket, and also disconnected the bell wire. There were no other extensions from the master socket. The Orange Netgear now indicated a sync rate of 4400kbps at SNRM 6db and attenuation of 56.3db. Within 24 hours, his line profile rose from 2000 to 3500 and he's happy. The phone was working fine both in and out - quite a quiet line.

My question is: just how did the phone manage to work before my rewiring? I understood that microfilters separate voice and ADSL, so how did voice get to his phone?
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jack21

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Re: Just How Did This Phone Work?
« Reply #1 on: May 08, 2012, 04:27:13 PM »

Sorry, I forgot to add.......the phone number before and after the rewire were the same.  If someone suggests the phone previously worked via VOIP, then would that suggest that both modems were in use and working on the one line?
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HPsauce

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Re: Just How Did This Phone Work?
« Reply #2 on: May 08, 2012, 05:46:35 PM »

I understood that microfilters separate voice and ADSL,
You understand incorrectly.  :blush:

The ADSL (RJ11) outlet is unfiltered.
The phone (BT socket) has ADSL frequencies "mostly" filtered out. (Not 100% effective though as I know from some strange experiences.)

Therefore: phones will ALWAYS work.  :graduate:
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jack21

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Re: Just How Did This Phone Work?
« Reply #3 on: May 08, 2012, 08:18:52 PM »

Ah, thanks HP, I surmised there must be good reason.

You've cleared up a similar mystery; another chap had a master socket and a single phone extension cable plugged into it, run under the floorboards and emerging at the top of a huge oak sideboard as a loose socket into which was plugged a microfilter, then phone, and also  ADSL cable to router. Router sync rate was (I recall) around 60kbps. But back at the master socket, the sync rate was 3800. Damaged/faulty cable think I, and we followed it back, bit  by bit, to where it emerged from underfloor to the back of the oak sideboard. Whoops, there was the unseen extension cable drum - with a built-in microfilter - with a phone cable plugged into the phone socket (ADSL socket was empty) and leading to the top of the sideboard where another microfilter was connected. In that case I marvelled at how any ADSL signal at all got thru! But as you point out, the filter isn't 100% effective, and hence I guess there was just enough to get 60kbps.
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HPsauce

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Re: Just How Did This Phone Work?
« Reply #4 on: May 08, 2012, 10:23:25 PM »

Exactly. Seen that many times.
You'll be an expert soon.  :graduate:
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