You shouldn't need to. Just putting the international dialing code (I assume this is what you want to do) should be enough. The phone will add the correct prefix for the country in use.
Thank You so much for the solution to my question.........I was beginning to think that my phone was losing its functioning ability.
Kind Regards
Arnold
Thank You very much for Your alternative solution to my query.
Having received two speedy accurate posts of information warms my heart in these troubling times.