@JB2016 Thank you very much for the link. That is exactly the informed, reasoned information I was looking for. Unfortunately, my original post seems to have attracted replies from others who did not understand the question or did not appreciate the possible implications of the "suck it and see" type of approach. I hope they will now follow the link you have provided. Once again, my grateful thanks to you - I had even got to the point where I was contemplating digging out an old Converter Ringing No4 but I think that would have been overkill!
@GeoffO1 One small correction to my test data. Where I mention two DECT cordless bases connected, two other phones with electronic sounders were also connected at the same time. Text has been amended.
@GeoffO1 If you don't mind, could you please let us know how you get on with your phones and the new hub? I sent the one I had back, as I already had an existing Voip system in the house. Be very interested to know if the Hub does work out with the mix of phones you have or if you do indeed resort to blowing the dust off the No.4.
@SRB I'm not due to be changed over to DV until the weekend and I'll probably start off with just the cordless but once I have the full setup in place I will certainly let you know how it goes.
@GeoffO1 @Thank You, much appreciated.