BT Phone Issues

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1 Feb 2014
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Hi,

I have a new BT line installed. It is distributed around the house over cat5, to rj45 sockets, where a RJ45 to BT line unit is fitted. The lines arrive at the master socket, then travel from there to a patch panel by a cat6 cable. The patch panel then distributes the phones to the sockets.

The issue is that when a phone is plugged in at a socket, the sound quality is awful. There is a lot of "humming" on the line, and the sound of a call will fade away before coming back up during the call. Typically 4 or 5 seconds into the call. When this happens the caller can still hear you clearly, but you cannot hear them. Occasionally the call volume does not come up again.

I have tested at the master, this issue does not happen, nor does it happen connecting directly to the patch panel. Would anyone have an ideas as to what might be causing this? Thanks
 
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Are you using pre-manufactured linemods at the RJ45 wall outlets? If so, the line should be going over a twisted pair (typically 4/5).

Disconnect the ringer wire in the master socket (3) - do the phones then still have dial tone? You may be picking your line up through the bell cap in error, due to incorrectly connect the master socket to the patch panel.

Photos?
 
Yes you need to be using a balanced pair (not any old two wires).
Check out EIA 586A or 568B (use one and stick to it for networking).

The other thing it is likely to be is the run of cat cable itself - does it route by mains circuits - especially noisey ones like lights with dimmers, non-iron transformers units, strip light ballasts.

If it varies a bit maybe you've some poor terminations, pull at the IDCs on the patch pancel (one wire at a time) and see if there's any change to the phone levels.
 
Yes you need to be using a balanced pair (not any old two wires).
Check out EIA 586A or 568B (use one and stick to it for networking).

The other thing it is likely to be is the run of cat cable itself - does it route by mains circuits - especially noisey ones like lights with dimmers, non-iron transformers units, strip light ballasts.

If it varies a bit maybe you've some poor terminations, pull at the IDCs on the patch pancel (one wire at a time) and see if there's any change to the phone levels.

I need to take the socket out, but as far as I remember, voice is on blue/blue white with the bell on orange. Would passing a mains line be enough to cause the dropping of incoming voice?
 
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Only if run in parallel for a length, or with dirty noise on the mains from dimmers etc.

Answer my questions, and ideally pics of back of master socket and patch panel.
 
Are you using pre-manufactured linemods at the RJ45 wall outlets? If so, the line should be going over a twisted pair (typically 4/5).

Disconnect the ringer wire in the master socket (3) - do the phones then still have dial tone? You may be picking your line up through the bell cap in error, due to incorrectly connect the master socket to the patch panel.

Photos?

There's pictures of the master, the rear of the panel (where I have daisy chained the sockets) and the linemod
 
What about the back of the mastersocket where the voice comes out? The removable lover half?

I assume that pink UTP cable bodged into the vDSL plate is just for your router/modem?
 
What about the back of the mastersocket where the voice comes out? The removable lover half?

I assume that pink UTP cable bodged into the vDSL plate is just for your router/modem?

Yeah the pink cable is cat6. I wouldn't really use the term bodged. It is correctly installed, the issue is that it is on an RJ11 connector, and the cable is far bigger than the connector, hence the joint between the crimp and the cable isn't the neatest
 
Cat6 for vDSL is not going to improve anything. A standard vDSL lead woud be fine.

On your pic of the rear of patch panel, where is the voice terminating?
 
Cat6 for vDSL is not going to improve anything. A standard vDSL lead woud be fine.

On your pic of the rear of patch panel, where is the voice terminating?

It was just a case of cat6 being all I had. It's a 2 metre or so run, I wasn't going to buy another roll of cable just for that. On the back of the patch panel, the voice terminate further over, on a blank patch. I then run a patch lead from there into the first socket of the daisy chained sockets. I found that punching the voice lead down on top of the already terminated IDC's where I had daisy chained it didn't give a solid connection
 
Most would terminate the voice directly to the rear, punching down without cutting, so just one cable in the IDC terminals.

I can't see the voice termination note patch panel too clearly, but other than that, things look ok.
 
Most would terminate the voice directly to the rear, punching down without cutting, so just one cable in the IDC terminals.

I can't see the voice termination note patch panel too clearly, but other than that, things look ok.

It's been suggested to me that this could be caused by interference from the data lines potentially running too close to the power lines (I didn't do the runs, I have no control over where they are) and there may be long (approx. 2m) close parallel runs. If this is the case, would installing a digital PBAX prevent this? I'm just thinking that with the lines being digital it might not be affected by electrical interference the same way analog may be?
 
How many bt points do you have ? I assume that they are all star wired off to a common point ?
 
How many bt points do you have ? I assume that they are all star wired off to a common point ?

yes, they are all star wired from a central "comms" room out to the rest of the house, at the moment I have 4 points, I didn't want to put any more on due to the REN number. I have the potential to run 48 points (but obviously that won't happen). Realistically, I would want maybe 6 points - I know a PBAX would be overkill, but I feel that it would be a way to eliminate this interference, if the PBAX was a digital ISDN system. I think...
 
We had the same issue with a job it was designed to have a PABX but the buyers didn't want one so the bt points where connected together and this caused the noise ... Try removing the points , do a quiet line test and add them back in one by one it may be just one point with the issue, but I think you may end up fitting a pabx
 

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