2 [non] VM replies - with respect @Paul_DN and @Paulina_Z why not try and help rather than pointing the OP to the phone lines which he has already said were not helpful
to the OP - not seen the letter and its the first time i have seen mention of it on here - but VM like all isp's ? are moving from the old land line system to voip - that means you plug your phone or an extension box into the hub - only the hub3 and hub4 have that facility so if you dont have either of those then you will need one - you need an adaptor to plug a standard phone in - not sure if VM now supply those as standard with the hub - if you have extension connections around the house then they will need disconnecting from the existing incoming landline and connecting to the hub in some way - i dont think VM will do that but they can fit a new master socket from the hub - they seem not to offer that unless
1 - you know about it and
2 - you ask
if for any reason you dont have a hub3 or hub4 and want to keep the hub you have then you cannot have a voip landline so you would need to remove that from your package and under normal circumstances that would start a new contract and [stupidly] may cost you more each month as you could lose package discounts
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Tony.