How do I use IDD and what are the rates? January 29, 2019 01:47 Updated If you have opted for the IDD call feature, dial: 1550 + the country code of the destination you’re calling + the local number Please visit our Business Voice webpage for the prevailing IDD rates. Related articles Is there a limit to the amount of IDD calls I can make? Can I choose or purchase a Business Voice number that I like? Business fix line Number Porting Service Application / Request Forms How do I check my Business Voice usage for the current month?