VOIP beginners help

Basically, I signed to Plusnet full fibre today, they lied and told me we could keep the BT Lifeline intact. Anyway, my dad received an email from BT confirming the cancellation of the landline around shortly after signing up, my dad received an email confirming the cancellation of the landline. I ring up Plusnet and they told me it will be cancelled with their full fibre. Does anyone know how to set up a VoIP system, and transfer the BT number over to the said VoIP system?

Many thanks

I would start by raising a formal complaint with PlusNet - their calls are recorded so their original promise to you should be recorded.#

Have read of what PN told me: https://forums.thinkbroadband.com/plusnet/t/4715448-...

And get a migration request to a VoIP provider as soon as possible. You may have a short beak in one service, but you need to recover teh situation.

I used Sipgate Basic as the VOIP provider and a Grandstream HT812 as the ATA for the phones.
The BT number was ported on the agreed day and the BT line ceased as a consequence.
It all went fairly smoothly. The original phone extension was connected to the HT812, and as the other phone was an extension off the first, both phones now ring on the old BT number.
As the phones are relatively modern, only two wires were needed.

Just an update to the situation for anyone who cares. I contacted Plusnet via twitter, and after a bit of to and froing, the line has been reinstated.