When collecting the users telephone number using the enrolment form (data collection form), you may want to set the default telephone country code to your locale. This will make the process quicker for the user as they won't have to scroll and find their particular country code.
A Membership/Loyalty card or Coupon design created
Data Collection form enabled with a telephone number field
First let's see how my form looks, you can see that the country code is defaulted to USA, so if I need a different country code I need to scroll through the countries to find mine.
Step 1 - Navigate to the Data Collection form design page.
Step 2 - Click on the telephone number field
Step 3 - Click on the "Default Tel Country Code" field
Select the Default Tel Country Code from the list.
Click save and you are finished!