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Why must I move my phones and plug them into the virgin media router with this CV21 upgrade? – You don't

Tuning in

I am writing this post, because although there is much of this information in other posts, I found it very hard to find and collate the various posts.

You want to leave your phones plugged in where they are … you can. It is possible to re-enable the existing sockets with this CV21 upgrade.

You already have the wiring round the house which extends your old ‘BT’ type (old virgin media) phone line to the phone secondary sockets round the house where you have and want your phones plugged in.

What needs to be done is for the new Virgin Media CV21 connection to drive those phone sockets, instead of the old ‘BT’ type (old virgin media) line.

In the virgin media documentation you may see this called out as  “This 'backfeeds' the new phone connection from the hub into the old extension sockets around the home to re-enable them.”



The master socket for the old telephone line has a faceplate which connects to the house sockets, and a backplate that has the old ‘BT’ type (old virgin media) line connected to it.

You can only drive the sockets around the house from either the new Virgin media CV21 connection from the modem, OR from the old line.

The steps that the Virgin Media engineer needs to do to achieve this are:

  1. take the Master socket off the wall and remove the old telephone line cable connected to the back plate (remove the old incoming ‘BT’ type (old virgin media) line) – this is not being used any longer.
  2. screw the master socket back to the wall
  3. using an RJ11 plug to ‘BT’ male plug cable / adaptor connect the telephone port on the Virgin Media modem to the faceplate (this will connect the modem telephone port to the extension sockets)

Note if the master socket is in the same room as the hub, great, plug it in there – but if not, once the old line has been removed from the Master socket, you can plug the telephone port of your Virgin Media modem into any telephone socket in the house.

Test that you can now make calls from your phones.

Note that the modem will have have to have been transitioned to CV21 operation

Before testing your phones around the house, or if they don’t work, plug a phone directly into the back of the modem to see if the fault is the connection to Virgin Media, or a connection problem within the house.


I hope this helps many of you out there.


We went through this with an engineer who visited my Mum.

Thank you very much to Ivan whose patience and willingness to work with us enabled to get this working, where 5 or so other engineers had previously failed.

Thanks too to Ivan’s manager who understood what was needed and supported Ivan in doing this work.


Just a quick caveat:

I have not done the investigations, but it is possible that the new CV21 link from the modem will not drive as many phones as the old ‘BT’ (old virgin media) line would have done, so if it doesn’t work first time, try unplugging all but one phone and then gradually plug others in – my Mum has 3 phones and an extension ringer plugged in and they ‘just worked’ as they should have done once Ivan had complete this change.


Forum Team
Forum Team

Hi stevehight,

Thank you for your post. I'm very sorry for any frustration you had with the change to the new phone line service. 

With regards to the work the engineer completed for yourself. This is something we would like to look into. 

What I will do is send you a private message you to confirm some details. Please keep an eye out for this. 




I have now had my line 'upgraded' to CV21 - Lawrence was my installer - very good installer and happy and ready to install the cable between the Router and my primary socket.


To disconnect the old phone line from the master socket, rather than cutting it at the back of the master socket - he cut it at the Virgin media junction box on the outside wall.  This worked just as well - first test and both incoming and outgoing calls worked well.


Work done in less than 30 minutes, a third or more of that time being us waiting for the modem to be modified to support CV21 - a phone call from Lawrence to Virgin media ... then waiting for the modem to reboot.


Thanks Lawrence, clean and easy switchover.

Hey there @stevehight, thanks for the update.

I'm glad to hear the install has been complete and that the engineer has explained everything thoroughly and also disconnected the old line on the network and also stayed to ensure that the lien was working on both ends.
We're always here if you need anything - feel free to reach out to us.

Kind regards.

Forum Team

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hello, I am just reading this after I received a letter from VM about posting an adapter, I am disabled and find this all very confusing, where must I plug into this adapter? Which I have not received as yet!.... Can I not have a VM Tec come and fit this for me? If not would I really lose the use of my landline phone? My landline is needed for emergency purposes related to my disability!! This is a very confusing time for me made so by VM. Maybe it would be just easier for me if I cancelled VM and went with some other cable company...Can someone help me understand all this cr*p I seem to be getting from VM, Please?

I cant access VM Home or anything that is VM except only this forum...I only get this:

Bad Request

Your browser sent a request that this server could not understand.
Size of a request header field exceeds server limit.

Hi Swifty-one, welcome back to the community. Thank you for posting and for joining this thread regarding home phone switchover. 

There's a couple of different issues you have mentioned here so I will deal with them each individually. 

1) The home phone switchover to 21CV service. Sorry to hear you have concerns regarding the switchover process! 

You can read more about the process in this Switchover Migration leaflet or on our Landline Switchover help page on the website, and here on the forum in this handy guide. 

We generally get in touch about 3 months before we are due to switch over your area. We are giving you advance warning of the process before it begins, which is why you may not have received your adapter just yet. 

We have a separate set of processes in place to ensure that vulnerable or disabled customers who are reliant on their landline service have access to this at all times. We can set you up with an Emergency Back up-Line (EBUL) which will make sure the landline is able to reach emergency services even if there is an outage at the hub. As long as this is flagged correctly on your account and to us in advance of the appointment, we will make sure this happens as part of your switchover. 

If it is the case that you require a manned installation appointment to complete the switchover we will of course also help book this for you! 

As you have not yet received the plug / converter we would need to wait for this to arrive before we can book an appointment in for you. Just let us know when this happens and we will be happy to help!

2) Your My Virgin Media access. In order to help with this we just need to ask a few troubleshooting questions first to isolate the issue:

- Have you ever had successful access to My Virgin Media? (If so, when)

- Are you trying to access via the Website or the My Virgin Media app?

- Have you tried clearing cookies and cache on the site?

- Does this happen when trying on more than one device? (Or is the issue isolated to a single device?)

- If possible, have you tried resetting the password?

Following your answer to these questions we can offer further support, and send you a PM if needed to get the switchover appointment booked in for you. 

All the best. 


Thank you for your help....I received the adapter in the post today, it seems a lot of work to reroot either, the phone cables or the VM router...I would need a technician to sort that out, please 🙂

As for getting connected to VM home/my VM, I cannot connect to any VM page, only to this forum, I have just updated Firefox v 106.0.2(64bit) I am on my gaming PC, and I do not own a mobile phone just my landline, I have cleaned out my cookies and cache. Yes, I have had access to all VM pages on this gaming PC, I cannot say when, but it has been some months since my last visit to, I am unable to gain access to reset any of my passwords. All links in your post I cannot gain access to ...What to do now, please? Thank you!


Thanks for the response on this swifty-one,

Just to clarify with the work that is needed to set up the phone line, is the Hub and the phoneline in different rooms?

Also is that "Bad Request" error happening on all browsers?

Let us know,


On our wavelength

Hello, Yes my VM hub and my phone line are in different rooms.

I have had this gaming since 2017...I have uninstalled all browsers except Firefox ..Firefox has been the default browser since 2017 and has been able to connect to VM without issues I had VM website as my home page, as I had my emails there, I had installed Mailbird as my email client in 2021 and still had my VM website as my home page, somewhere between late 2021 and early 2022 I stopped using VM as my home page this was also the reason why I missed what was happening with the phone service.


No worries thanks for the response on this.

Regarding the 21CV upgrade I've dropped you a PM.

The message will appear within the purple envelope icon.