BT are "phasing out" their retail internet connection moving it all to EE - same company but different branding, different pricing and different customer services.
And plusnet are also part of the same group as EE.
If you want to keep a landline, and are with Plusnet, you are going to have to move to EE (or pay a separate VOIP provider while continuing to get just broadband from plusnet).
We definitely want to keep our landline, because mobile reception here is crap. It will no longer be a dedicated landline, but will be via an adapter, built in to the EE modem/router, which we will plug our existing phone into. Should be able to keep the same number, and prices won't (initially) change.
And because the plusnet emails recently moved to Greenby, we will be able to keep that too (though I don't use it, my wife does).
We will be moved over in the next few weeks unless we tell them we are happy to go with a broadband only service from Plusnet. Even though Openreach don't currently have a planned date for FTTP for our premises (FTTC already in place).