I have two Digital Advance phones and it works really well. I had to select the feature on the phones menu so I presume it is the feature of the phone rather than the SH2.
But I could be wrong!
Had a problem with that. One call was on a wired phone and a second call came in on the advanced Alexa phone. The second call was answered ok but the wired call went "one way transmission". Have not got round to reporting this yet. The other day an incoming call answered on a wired phone went "one way transmission" on answering. BT suggested rebooting the smart hub which cured that but for how long?