Effectively I gave up, the Digital Voice Adaptor (DVA) was clearly not fit for purpose probably because someone having designed it to a spec that had carelessly omitted voice ID so it only worked occasionally.
BT eventually agreed it was an issue so sent me one so called 'Advanced Digital Phone for free and I had to buy two more for £73. To be fair they are pretty good phones. My DVA is sitting unused in a cupboard somewhere.
I had hoped by now BT would have long ago sent a terse note to their Digital Voice Adaptor supply chain to demand they fix the issue pronto so it's disappointing that after all this time they apparently are sending out DVAs that not only still don't work properly but BT have long known this to be the case.
I suggest point this out to them using this thread and see what offer you can get out of them.
The whole Digital Voice changeover has been a fiasco for which I mainly blame OfCom who were well and truly conned by the phone companies submissions and didn't challenge them.
