AWS Messaging & Targeting Blog

Improve SMS Message Delivery with Phone Number Validate in Amazon Pinpoint

Edited June 18, 2018: Since we first posted this blog post, we’ve changed the name of this feature to Phone Number Validate. Additionally, this feature was initially only available as a preview for customers who completed an application process. As of today, Phone Number Validate is available to all Amazon Pinpoint customers.


SMS messaging is becoming an increasingly vital tool for companies in a variety of industries and across a diverse range of use cases. For example, many app developers use SMS messaging as part of their process for onboarding new customers. When new customers sign up for a service, they’re asked to provide their mobile phone numbers. The developer sends the customer a one-time password in an SMS message, which the customer then enters into a form on the web or in an app to complete the registration process. This capability is an important tool for ensuring the security of customers’ accounts. However, if the customer doesn’t receive the SMS message that contains the one-time password, he or she may become frustrated, and might abandon the registration process completely.

There are many things that could prevent an SMS message from arriving, but the most common causes are data entry errors. Apps and web forms typically only perform basic verification of phone numbers that end users provide. For example, they might check to make sure customers only entered numeric characters, or that the number contains the right number of digits. When customers enter their mobile numbers into an app or on a web form, they might accidentally enter their country code twice, or not enter a country code at all, or enter a leading zero in front of their phone number, or any of a variety of other common errors. In some cases, customers might even enter numbers that aren’t capable of receiving SMS messages, such as landline or Voice over IP (VoIP) numbers. Basic number validation techniques won’t stop any of these common errors from occurring. To help our customers find and correct these common issues, we’re launching a new feature in Amazon Pinpoint called Phone Number Validate.

With Phone Number Validate, Amazon Pinpoint checks to see whether the phone number provided is in a valid format based on its country code prefix. If the number is formatted correctly, Amazon Pinpoint leaves the number as the customer entered it. If the number isn’t formatted correctly, Amazon Pinpoint compares the phone number to various rules to make it valid. For example, if a customer enters a leading zero after the country code, Phone Number Validate removes the extra character to make the number valid. In this case, if the customer entered +1 0 206 555 0199 (a United States phone number in the 206 area code), Phone Number Validate changes the number to a correctly formatted number without the extra zero (+1 206 555 0199).

In addition to formatting numbers properly, Phone Number Validate can also detect and fix country-specific nuances. For example, in Brazil, older mobile phone numbers had eight digits. To create a larger pool of possible mobile phone numbers, Brazilian mobile companies added a ninth digit, and added a 9 to the beginning of the older eight digit numbers. If a customer provides a Brazilian mobile number that contains eight digits, Phone Number Validate detects the issue and automatically insert the 9 in the appropriate place, between the area code and the phone number. In this example, Phone Number Validate would change +55 11 9123 4567 (a number in country code 55 and area code 11) to +55 11 99123 4567. By capturing and addressing these issues at the time of entry, Phone Number Validate can potentially increase the number of customers you’re able to contact. Our internal testing shows that up to 10% of mobile phone numbers contain these kinds of errors—that’s 10% of your potential customers that you might not be able to contact otherwise!

Phone Number Validate also returns metadata about phone numbers, such as the name of the telephone carrier, the type of phone number (landline, VoIP, mobile), and the geographic location (city, country, state and time zone) where the number is registered. Amazon Pinpoint users can use this metadata to perform additional validation. For example, if a user provides a landline number, you can immediately prompt the customer to enter a phone number that is capable of receiving text messages. Alternatively, when a customer provides a landline or VoIP number, you can call the user by using text-to-speech technology, rather than by sending a text message.

Phone Number Validate is now available in Amazon Pinpoint. For more information, see the Amazon Pinpoint User Guide and the Amazon Pinpoint API Reference.