Who knows what the global cost of mis-dialling phone numbers is.
Today’s invention is simply to equip handsets, both mobile and landline, with the ability to say, via speakerphone, the numbers you have keyed in (either digit by digit or after the whole number has been entered).
My guess is that this would be significantly more effective than squinting at a small screen to check your dexterity.
A possibly useful extra service, for for those of us calling lots of unfamiliar numbers, might be to speak the name of the (directory-listed) person or company you are about to call.
If, despite all these measures, you still dialled a wrong number, the phone could be configured to allow you to record this manually and then extract statistics about what sorts of errors/ substitutions you habitually make. It could then take extra care to alert you to these in future before pressing the call button.