How to Validate Phone Numbers for Apps

If you have an app, you need phone numbers. If you’re not using phone numbers in your app, you need to start.

Phone numbers can simplify your app and make life easier for your users. And, that’s in addition to increasing security. Some companies, like the Affirm lending company, use phone numbers instead of usernames and passwords.

But, regardless of how you use phone numbers in your app—to send SMS messages for two-factor authentication, person-to-person communication, text notifications, or anything else—you need to validate those phone numbers.

Here’s why you need to verify phone numbers in your app, and how to do it.

Why validate phone numbers?

First and foremost, you need to know what sort of phone number you have.

Landlines can’t receive text messages. So, you need to at least identify and separate the landlines from the cell phone numbers. That way you don’t waste text messages.

And, you need to make sure the phone numbers are correct. People make mistakes all the time when they enter phone numbers. And, people often give fake information, for fear of excessive marketing messages and harassment.

If you don’t validate phone numbers, you’ll waste a lot of text messages (and therefore money). And, your customer experience will suffer. People often won’t realize they’ve made a mistake entering their phone numbers. So, users will get frustrated when your app doesn’t work as expected. This causes excessive app abandonment.

Fortunately, validating phone numbers is easier than you might think.

How to validate phone numbers for your app

There are a lot of ways to validate phone numbers in C# and C++, with Python, or using Javascript. However, these methods require a lot of development. And, it’s just more code to debug and potential for development delays.

You have to choose a phone number validation regex. Some regex syntaxes work better than others. 

Additionally, most regex methods only verify that the phone number is an actual phone number. Phone numbers will pass the regex check as long as the phone number has the right number of digits and there are no letters or other characters.

But, a valid phone number can be disconnected. And, the validity doesn’t tell you what type of phone number it is.

Then, there’s no central database of phone numbers that you can download and use for your app. It’s impossible to independently determine whether or not a phone number is connected or not, or if it’s a cell phone or landline.

Also, an internal regex check doesn’t tell you if phone numbers are on the DNC list or not. You can access the DNC list. But, it’s updated constantly. So, you’d need to constantly update any DNC database you create.

So, it’s easier, more thorough, and usually more cost-effective to outsource the phone number validation for your app. It shortens development cycles and makes your phone number validation more reliable.

This is how it works.

Integrated phone number validation

Rather than trying to add custom snippets of code to your app and experimenting with a phone validation regex, it’s much easier to use a phone validation API to connect your app to a data verifier.

A quality data partner will have access to multiple data streams to validate phone numbers in real time, on demand. And, the best phone validator API requires no API key. You just need a unique URL that’s generated using your account info.

All the phone validation code is replaced with a simple API call.

Then, add a phone validator API call to the interface where users enter their phone numbers. That way, phone numbers are automatically sent out to your data partner for validation whenever a user enters their phone number. The phone number is checked fast enough that there’s no impact on the user experience.

This checks to ensure that the phone number is syntactically correct. The phone validator also checks to ensure the phone number is connected and usable (not on the DNC list). Then, it determines if the phone number is a cell phone, landline, or VOIP phone number.

The phone number validation API does all the work for you. The only thing your proprietary code needs to do is gather variables from the API results and do a few if/then checks to determine what it needs to do. 

If a user enters an invalid phone number, your app can prompt them to correct it. And, you can ask the user for a cell phone number if they enter a landline, or vice versa.

Then, you can automatically suppress text communication to landline phone numbers.

Additionally, using a phone validator API to validate phone numbers eliminates user experience issues from disconnected phone numbers and data entry errors.

Validating your phone numbers can also save you from hefty TCPA fines, since you’ll know if a number is on the DNC list. And, you can easily use an API call to check phone number before you call or text that number and ensure that it wasn’t added to the DNC list since you last used that phone number.

In short, using a phone validation API simplifies your code base, saves you money, and creates a better user experience. All this while also making your app more efficient since you’re outsourcing some data processing.

Phone number validation cost

Any good app developer wants to know how much an API will add to their operating costs. When you’ve got thousands or millions of phone numbers to validate, it’s easy to imagine that the cost would justify doing everything in-house.

But, most of the time, verifying a phone number costs a penny or less. And, the more numbers you verify, the lower the price-per-number gets. So, it’s cost-efficient to validate every number that’s entered into your app, and check numbers again before you contact them. And, the costs get better as your app grows.

The price of validating phone numbers is actually low enough that you could develop an app that validated phone numbers for people for a small fee with a strong profit margin.

What to do now

Obviously, we can only guarantee those prices and API performance if you use the Searchbug phone validator API. Other data providers may not have the data streams to verify phone numbers in real time for the same price-per-validation.

If you need verified phone numbers for two-factor authentication, text notifications, peer-to-peer calling, or any other app operations, it’s time to check out the Searchbug phone validation API.