Can I communicate with my customers if the country code is not included in their phone numbers?

Can I communicate with my customers if the country code is not included in their phone numbers?

For seamless communication, it’s better to have contacts saved with their mobile or phone numbers, including the country code. If a contact record is saved without a country code, tapping the WhatsApp quick action icon from the Contact Details View Card may sometimes prompt you to invite the provided number to WhatsApp.