When importing a record containing a phone number into Business Central any phone number containing letters will return the error message “Phone No. must not contain letters”
The BC field type “Phone Number” does not allow any letters. An example of an invalid phone number is:
Invalid: +45 26260101 Ext 123
Valid: +45 26260101 #123
Use a calculation in SmartConnect to strip invalid characters from the phone number prior to importing to Business Central. Below is a sample calculated column I have used to resolve this error.