A small note "If a local number starts with a single 0, strip the 0 and prepend the country code" is FALSE for at least Italian numbers.
For instance Turin, Milan, Rome and Genoa landline prefixes are 011, 02, 06, and 010. Any landline in Italy start with a leading zero BUT you can't strip it.
Let's say a Rome landline 061234567 can't be called like +3961234567 it MUST BE +39061234567. On contrary in France where essentially all numbers (mobile included, witch in Italy start with 3, no leading zero) start with zero you MUST cut the leading zero when you call it with an international prefix.
That's why in some countries the leading 0 is written as (0) meaning "you might or might not need it depending from witch extension of witch country you originate the call".
For instance Turin, Milan, Rome and Genoa landline prefixes are 011, 02, 06, and 010. Any landline in Italy start with a leading zero BUT you can't strip it.
Let's say a Rome landline 061234567 can't be called like +3961234567 it MUST BE +39061234567. On contrary in France where essentially all numbers (mobile included, witch in Italy start with 3, no leading zero) start with zero you MUST cut the leading zero when you call it with an international prefix.
That's why in some countries the leading 0 is written as (0) meaning "you might or might not need it depending from witch extension of witch country you originate the call".