If a programmer enters a wrong phone number or mobile number or enters email-id in a different format, it shows an error message and asks the user the correct phone number and email-id.
Most telephone networks nowadays are interconnected in the international telephone network, where the format of telephone numbers is standardized by ITU-T in the recommendation E.164, which specifies that the entire number should be 15 digits or shorter, and begin with a country prefix followed by an area code or city code and the subscriber number, which might consist of the code for a particular telephone exchange.
In writing an international telephone number should start with a plus sign (" ") and the country The " " stands for the international call prefix chosen by the country the call is being made from.
Since we are using This will show the text of the input in green if it’s a valid number or in red if it’s an invalid number.If you want to learn more about Promises check out this post. We can now verify phone numbers without using regular expressions!Now that we have a way to verify a phone number on our server we need to connect it to our input field and verify the number while the user is entering it.For that we need to write a bit of server-side code.The Lookup API is useful for a variety of things such as determining the country of a phone number, the local formatting of the number, the carrier associated with the number, or in some cases even the caller name.