This function confirms whether or not a value is a valid US phone number. The function returns true if the syntax is valid or false if it’s not. Any non-numeric characters are ignored on evaluation.

Sample phone number strings and their resulting evaluation by the function are provided below.

Phone Number Result
234-235-5678 true
234 235 5678 true
(541) 754-3010 true
+1-541-754-3010 false
1234567890 false



Ordinal Type Required Description
1 String True Phone number to validate

NOTE: This function will only validate US phone numbers. Other country formats will return a false result.


When a landing page form is submitted, an phone form field is validated and an alert message is displayed if the syntax is invalid.

%%=Iif(IsPhoneNumber(RequestParameter('phone'))==false,'<div class="alert">You have entered an invalid US phone number</div>','')=%%


A value of 0402 123 456 will return the following output.

<div class="alert">You have entered an invalid US phone number</div>