When we were last with BT, prior to the introduction of Digital Voice, we could divert our phone to another number and when that diversion was active, the dialling tone would change to an intermittent one. Thus we could easily check if it was still 'on'.
Now, with DV, the tone is the same regardless of whether diversion is active or not. I have already missed a couple of urgent personal calls (the line is mainly 'business' during office hours as I work from home and so they divert to our paid business telephone answering service).
Why did BT not preserve this useful feature? It may seem a minor thing, but at the moment it feels like DV has been a downgrade to the service.
DV has ability to make and receive a call at same time or make 2 calls at same time but you can change this by changing calling line feature from multi to single and that may help