Phone landline and internet doesn’t work at the same time

[Atlanticflyer]

Novice here, really confused. 
For the past 5 days my landline has not had a dialling tone and whenever someone calls they hear an engaged tone. For couple of days the internet keep dropping every 5-10 minutes, looking at the router I can clearly see the lights flash red and sequence through amber and eventually turn green. This now seems to have resolved but the difficulty with landline remains. 
I have changed the dsl filter and when doing this I forget to plug the modem back into the phone socket, instead the I plugged the filter with the phone attached into the phone socket and the difficulty with the dialling tone was resolved. However, as soon as I plug the modem and dsl filter into the phone socket the internet works but still no dialling tone. 
Any ideas what is happening or what I’m doing wrong?

[Atlanticflyer]

1. Photo attached, behind the splitter is the cable that takes the phone line to the modem. 
4. Diamond has never worked. Was for cable tv but it’s never been connected since I move in 20 years ago. 

many thanks for trying to help. 

[Ian06]

Just to clarify the telephone splitter (circled in red) appears to have an extension cable coming from it running round and back into the wall or behind the phone socket.  Do you know what that connection is for?

When you remove the phone splitter (red) and plug the dsl filter (circled in blue) into the phone socket what happens?

The socket on the "Diamond" box looks like a master phone socket have you removed the lower front face plate from the "diamond" box to check what is connected to it?

Also just to be clear then internet modem/router should be plugged into the DSL filter in the socket marked Modem and the phone plugged into the DSL filter marked Phone.  The DSL filter should be plugged directly into the master phone socket with nothing else in that master socket.

If you had Broadband Internet installed in the last few years the master phone socket should look like the one XRaySpecx posted a picture of earlier, when was this installed ad how long have you had broadband from EE?

[Atlanticflyer]

Thanks for your help. The photo is only showing as a triangle, I can’t see your picture. Sorry. 
been in the house for 20 years and the diamond box has never been connected and never used. It’s been many years since broadband was fitted. 

[James_B]

We've approved the picture @Atlanticflyer, so you should be able to see it now.

James

[Mustrum]

@Atlanticflyer   I have authorised the pic now so you should be able to see it.

I think it would be best to give the Broadband Care team a call to get Openreach out to sort out your socket and wiring. It is very old, and that splitter is just adding to the confusion. 

[Atlanticflyer]

Thanks for the advice. I had a feeling it was the hardware. 

[XRaySpeX]

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@Atlanticflyer wrote:

1. Photo attached, behind the splitter is the cable that takes the phone line to the modem. 

The DSL cable for the router should never be plugged into any phone socket, but into a filter. That's why it's not working.

I suspect that the newer "Diamond" socket has been installed as a proper main socket off the older non-split socket.

Take the router cable out of the back of the splitter & plug it into the "Modem" socket of the filter. Then plug the filter into the phone socket that you are currently using or better still plug it into the "Diamond" socket & see if that works. If it does continue using it in future.

Bin the splitter.

I don't see how that arrangement ever worked.