Adding country codes to a phone number... Please help

How would I add a country code to a phone number using a formula?

I need to add a 61 to a phone number if it starts with a 4, for example.

417566504 (this is the number now)
61417566504 (number after)

Any help would be appreciated.

Never mind done

=IF(LEFT(D1,1)="4",61&D1,D1)