True call works well, but the issue is that often they do not show any number. I find this is often true of councils, NHS etc, so really there is nothing one can do about this. With the widespread use of such devices due to the failure of the telephone pref service to stop rubbish callers, its going to be up to the organisations to at least use a known number for the star or whit list. This is my opinion. I am aware its becoming an increasing problem for large companies who do not show a number. The ball is in their court and their records should show that there were issues with the calls to some numbers by their short duration and hence flag up them to call you with a human or send you a letter in my view.
Alternatively, you could just give them only a mobile number but increasingly, there are junk texts and calls coming into those as well. I think even the services operated by companies like bt have the same problem with automated calls. I do not know the answer unless they only allow the message to play if your end is asked to hit a # key or something, then they would know which calls failed. Brian