Wiring Help

[#1]

That looks like a PABX master - a ring capacitor but no spark gap/resistor.

[#2]

Sorry HP, as this is a 90+ flat building I wouldn't advise that, just terminal 3 as detailed below.
Yep apj, that's a master. But neither of those cables may actually be the incoming cable, it may be on the other socket with two cables in the Hall - more likely as there an RJ45/RJ11 there, and the reason the master is here is because of the modular socket in the hall, strange way of doing things but understandable to a degree, but go and talk to the maintenance people about where it all goes, where the building distribution point is etc.
One thing that will probably help (but in part depends on what's going on at the Main Distribution point) is at this Master socket just remove the wires from terminal 3, that's the Orange ones (bell-wire) by gently pulling them vertically from the terminal. Make sure all the other connections especially 2 & 5 are secure at all sockets. Just tuck the Orange wires back out of the way so they don't touch anything.
Make sure that 2 & 5 are secure at the other sockets. Plug a phone with a filter in to the one that you screwdrivered back and check that you don't get any extra crackles if you gently manoeuvre the wires on terminal 2 & 5. I did note earlier that someone has removed the wires from all the other terminals here, not much use really as it wasn't the Master, oh well, don't worry about it just leave it, no point in reconnecting them.

[#3]

Re:Openreach access, did you ask if it was limited hours or 24/7?
Did they tell you what the RJ45/RJ11 socket was connected to?

[#4]

They'd rather during office hours, but someone is on site 24/7.
They didn't know where the ethernet wire leads or what it was for - they said Openreach would tell me if they came.

[#5]

Quote from: Anotherone

Sorry HP, as this is a 90+ flat building I wouldn't advise that, just terminal 3 as detailed below.

I don't understand that, please explain.
If some other flat's service is using wires 1 and 6 (and 4?) that would be highly irregular and potentially dangerous.
It just looks like it was wired up using 6-core cable by a lazy/knowledge-poor electrician. 

[#6]

Okay, I pulled out the solid-orange wires from terminal 3 in the bedroom socket - the one with the capacitor, although not necessarily the master! Quiet line test here is now clear, not crackly like before. It's also now clear on the RJ45/RJ11 socket, but I pulled the orange wires out of there also, for completeness.

[#7]

Quote from: HPsauce

Quote from: Anotherone Sorry HP, as this is a 90+ flat building I wouldn't advise that, just terminal 3 as detailed below. It just looks like it was wired up using 6-core cable by a lazy/knowledge-poor electrician.

8-core more like, the solid-brown / stripy-brown are folded back! Looks like CAT5 to me...

[#8]

You're right, Cat5, I didn't look closely enough. 
The electrician comment still applies. 

[#9]

My reason for that HP is it's a Management controlled building and isn't really necessary, as you know the bell wire is the critical one.
His installation has been working fine upto now (when the crackle appeared) and at good speed IIRC.
I doubt that because of the nature of the building that it will have been done by any one that wasn't working to some pre-defined plans and there will be nothing "dangerous" about the installation. It's Cat5 cable as well. He could be breaching the terms and conditions of his occupancy by "fiddling" with things, so in my book best left alone except for what's essential (the bell wire) to give him the chance of the best possible performance.
@apj, If everything now seems ok, refit the sockets and check again for crackles with your phone + filter. If all still ok, reconnect the modem/router and see what your stats are looking like. Keep an ear on the Quiet line test and pursue a fault if need be.

[#10]

If removing 3 I would also remove 4.

[#11]

Guys, thanks for all your input! Line noise is gone completely. My line attenuation has dropped by 1dB exactly in each direction, and sync speed in the 17000s.

	Link Information
Uptime:	0 days, 0:01:14
DSL Type:	ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]:	828 / 17,017
Data Transferred (Sent/Received) [kB/kB]:	24.86 / 37.31
Output Power (Up/Down) [dBm]:	12.2 / 20.8
Line Attenuation (Up/Down) [dB]:	11.0 / 23.0
SN Margin (Up/Down) [dB]:	8.8 / 6.0
System Vendor ID (Local/Remote):	TMMB / ----
Chipset Vendor ID (Local/Remote):	BDCM / TSTC
Loss of Framing (Local/Remote):	0 / 0
Loss of Signal (Local/Remote):	0 / 0
Loss of Power (Local/Remote):	0 / 0
Loss of Link (Remote):	-
Error Seconds (Local/Remote):	0 / 0
FEC Errors (Up/Down):	16 / 97
CRC Errors (Up/Down):	0 / 0
HEC Errors (Up/Down):	0 / 0

[#12]

Looking good, hope that it stays stable