Hey Colm,
You can update the country code by clicking the “User Icon” 
in the top
right corner and selecting “Profile & Preferences”.
Select “General” on the left hand side and go to the “Profile” tab.
If you scroll down you will see the option to change “Language”, “Date,
time and number format” and “Phone number” to reflect your local region.
Once you have updated these options the default country code will change
when adding a new phone number.
Hope this helps 