You are 100% right, Paul! I went home and had a really good look at my phone. The position of the zero was what confused me from the start.
This also explains the problem a friend of mine had with his pulse dial phone. It has buttons, not a dial. When you dialed a phone number you ended up at someone with a number displaced one position:
445533 became
334422
(or if it was the other way round)
We eventually managed to set it to tone dial.
