Sept. 11, 2024
Have you ever wondered how online businesses are able to tell if a phone number is real or not? In a digital age in which security is more important than ever, confirming that a phone number is really tied to the person using it is a major challenge for many businesses. This is where API phone number verification comes in. Automated verification to confirm the phone number given is the person trying to access your services. We'll be covering why you should care about this sort of verification, different verification methods, and how you can implement these systems yourself to improve user onboarding by the end of this post.
You'll walk away with actionable insights to improve your own verification processes and keep user data secure.
API phone verification is a thing on the internet that allows you to check if a user's phone number is real using a series of automated checks in a system, so that you can make sure it's not a random made-up number, and that the person signing up/logging in is the person they say they are. With API phone verification, you can automate this process with technology so you don't need to check it manually.
This allows businesses to verify their users easily, with a little bit of security to keep their accounts safe, and give their users a little peace of mind that nobody else can take their account that easily.
Phone verification is used to give you peace of mind that a user is who they say they are, and that's partly why it's being used more and more by online services. It's a tool that helps fight fraud and is a safety standard for business and consumer. As everything is put online, it's more important to protect people's personal information. With phone verification like SMSing a one-time passcode (or some other way) it's super easy for a business to verify if someone really is who they say they are before giving them access to important information or services. This has now become just a normal thing for a lot of things, from finance to e-commerce where trust is super important.
By using phone number verification like API, you can make a lot of this easier for developers and users. By automating verification, we're actually enabling a system where you can verify an identity quickly, without much delay. And because these APIs are so easy to integrate and easy for a user to understand, there is very little friction or confusion on user onboarding, and you get a really nice customer experience. For developers, automating verification means they can focus on the rest of their application knowing their verifications are being done securely in the background.
APIs can do this in several ways, such as checking the line type to see if the number is a mobile, landline, or VoIP service, validating the number format, and sending verification codes via SMS. That way, you not only simplify verification, but you can also target your users based on what kind of service they have. For example, SMS might be more suitable for verifying the number of a mobile user for mobile user engagement, while some other means might be more suitable for other things, e.g. automated phone calls for landlines.
When it comes to phone number verification, accuracy and speed matter. A lot. They're key to earning user trust and delivering an onboarding experience that users will love. Today's users want a verification process that's fast, and that gives them confidence their data is secure. And you'll decrease the time it takes for a user to register for your product. If the process is too lengthy or requires too much user input, you may lose potential customers who abandon their registration—and that can be devastating for your business. That's why you need more than secure phone number validation. You need to make sure the user experience is excellent so you can keep your users happy and increase your customer lifetime value.
In today's digital world, communication is crucial. You'll want your phone number to be accurate and contactable by businesses. There are many phone verification methods to verify your phone number you can use with different strengths and weaknesses to keep your business safeguarded from fraud and to reach the people you need to reach!
Real-time phone number validation is kind of like proof in the pudding. It's the ability to know in the moment whether a phone number is real, and actually being used, right as someone hands it over to you. It's usually done via API. Businesses can immediately check the phone number they've just received to make sure it's a real phone number. The customer gives you their phone number, the API checks to see if it's in the carrier's database of active phone numbers in real time.
It's useful in many use cases such as when people sign up for your app, or when you want to use SMS for your business. You'll receive higher-quality data with fewer errors at the point of entry so your users have a better experience. But it will probably cost you. Usually, per validation.
Regular expressions (regex) are very useful for validating phone numbers by ensuring the phone number is formatted correctly. This is helpful because you can use regex to ensure that a phone number displays the expected structure, which will help you filter out records that don't match known phone number patterns. So with regex, you can prevent incorrectly formatted phone numbers from entering your system. But you still can't tell if that phone number is a working, connectable phone number.
Why not? Because a phone number can pass regex validation and still be disconnected, or belong to someone else. This would be used in conjunction with other methods to simply filter out the garbage as a first line of defense. As a business, keep in mind that while regex will catch the majority of basic validation issues, it should not be the only tool in your validation toolbox.
Database checks are a key part of phone number verification because they use the phone number to look up information from a database. The database might be a public directory, telecom records, or some private data that you own.
When you do the lookup, you can find out whether the phone number is valid, and sometimes you can learn that the number belongs to a person or business.
The usefulness of a database check boils down to the quality of the data. If the database is outdated or full of mistakes, then it won't do you any good. But when used effectively, database checks can yield substantial returns, especially for businesses that need to clean and verify their customer databases or want to bolster their marketing efforts.
Token-based verification is the most common and secure way of verifying phone numbers. You ask for the user's phone number, then ask them to look at their messages for a one-time password (OTP). They’ll input the OTP into your system and then they're good to go.
You can use it to verify that the user has access to the phone line, and, for extra security, that the person using the account is the one with the phone number. Often used for two-factor authentication (2FA) in sensitive transactions so the wrong person doesn't send themselves money. But it's its own technical setup and may require more resources to implement.
The older way to verify a phone number is line testing, which basically means calling the number in question. Line testing is a quick and easy way for businesses to determine whether a phone number is live or working. By using the result of the call—whether it rings, whether it is answered, whether it goes to voicemail—businesses can make an educated guess whether the phone number is active.
Line testing gives you the phone number status straight away, but it isn't the most cost-effective because you have to spend the time and resources to make those calls. However, some businesses like the peace of mind and may get more detail from this process, such as whether the phone number is a mobile or a landline.
When used together, you'll be able to ensure you are maintaining a reliable and accurate communication list and have an easier marketing and customer service experience. Each method has its own limitations and is beneficial for certain uses and budgets.
For secure user authentication and fraud prevention, you'll want to include phone verification in your app. Here are some API integration examples where you can test user phone numbers quickly with SMS and voice solutions.
Twilio's API is a great way for developers to quickly add phone number verification. With One-Time Passwords (OTPs) sent and verified through just a few lines of code in any programming language, you can dramatically simplify the process of verifying your users. There are functions you can use to send an OTP over SMS in just a few lines of code, and another to check that the user entered the right one. This means you can reduce the chance of malicious actors gaining access to your app and have a more secure application.
Even better, Twilio is so flexible you can use it easily alongside what you already have set up so the end user has a seamless experience. For instance, in a mobile app, you could use Twilio's SMS API to verify that a user really is who they say they are by sending them a code unique to their phone number -- then they enter the code and they can create a new account or log into an existing account with confidence.
Firebase phone auth is another great way to help you handle user sign-ins. With Firebase you can easily sign users in using their mobile number, making the sign-up and login process a cinch. The Firebase SDK is easy to use and straightforward to integrate into your app, so you can rest easy knowing that mobile number verification is secure.
You can begin collecting phone numbers, sending OTPs and verifying your users' identity all without writing a ton of backend code. Available on Android, iOS and web, it's great for cross-platform developers and saves you tons of time, avoids potential security holes and helps you keep your user data in line.
In addition to 2FA, the Sinch API has a ton of other options that are more flexible, like you can use SMS and voice. With Sinch, you can pick how you want to verify your users, whether you want to send them an SMS with a code, or do a one time passcode over a voice call. This could be especially important if your users are more likely to have access to one type of communication channel than another.
Plus Sinch's platform also has phone number validation and fraud protection features to ensure that the only people on your platform are real people. They're designing phone verification more holistically, so that when you use Sinch, you're secure, but also have a good user experience. Overall, the Sinch API is a total solution for creating a secure, authenticated experience for your users.
As a Django developer, you can leverage the Django ecosystem and Twilio to create a phone verification system using Twilio's SMS API that seamlessly fits your application.
In a nutshell, you'll create a model to store phone numbers, a view to receive user input, and use Twilio to send the OTP. When the user enters the code they received, the API will confirm that it matches the one that was sent, giving you a user-verified identity that you can use for logging in or signing up. This is an example of how you can integrate SMS APIs into existing web frameworks in order to add security and user experience.
The Google SMS Retriever API makes phone number verification easier in your app. No need to ask for additional SMS permissions. You can have your app automatically retrieve the verification code for a better user experience. The user will still receive an SMS with the verification code, but they won't have to leave your app and type the code manually as they would with the old process.
Which is useful because it means less typos and less of a headache for the end user. With just the SMS Retriever API, you can speed up the verification process and get your users signed into their accounts quickly and easily. This not only saves time but also user engagement. They're more likely to complete their signup flow when it's seamless and doesn't interrupt their app experience.
I used to think phone number verification was nonsense. Like, why would anyone want my phone number, and why would anyone want to verify my phone number? Is it so they can hack into my Tinder account or something? Why don't they just use email like a normal person? I was so young and naive.
But as I grew older and wiser, I began to understand the need for phone verification. Now that I'm a grownup I totally get why companies want to verify my phone number.
Here are 10 reasons you'll want to use a phone number verification API for your business, and 3 reasons you won't.
Phone number verification helps prevent bad actors from gaining access to your app or platform. Phone number verification APIs are what companies use to keep app users safe. They're a wall between your app or platform and the fraudsters. Phone number verification API is something you can add to help protect your app, platform, and business.
One of the main reasons to use phone number verification is that it's more secure. By verifying the user's identity, you're virtually eliminating nearly all fraud. Having the user verify their phone number at registration gives you that additional layer of protection. If a bad actor does get the mobile number associated with an account, it's difficult for anyone other than the user to access that user data.
For example, a fintech app that verifies users' phone numbers. If a bad actor tries to register fake information and can't pass the verification, the business has locked down their app and secured the real user's information. This increases trust and shields the business and users from fake identities or unwanted activity.
Phone number verification is also a powerful tool for accelerating the user onboarding process. When a user signs up and enters their phone number, we can verify that the phone number is real, enabling real users to sail through your signup flow faster. And quick sign-up speed is especially important in competitive markets where a user might bounce and not want to fill out long registration forms or jump through hoops for verification.
For example, a startup might use the phone verification API to auto-text users as soon as they register. With a simple entry of that code, they can skip huge vetting processes and rest easy knowing their data is secure with the verification system in place.
One of the best use-cases for phone number verification is for MFA. By sending a one-time PIN (OTP) to complete the sign-in process, system administrators can add an extra layer of security to user accounts. This not only helps to ensure the right person is trying to access your app, but is also reassuring for users that their account is secure.
Take e-commerce for example. If someone tries to log in, sending them a unique code means they need access to their registered phone so they can't easily get in if they don't have access to that phone. MFA via phone verification is a great way for 100% locking down accounts from being accessed by unauthorized users, which is reassuring for users that your app is secure.
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When you're verifying phone numbers, you often have to pay over the odds. This can put small businesses and startups at a disadvantage. As you get more and more users, the cost of sending SMS messages or using more resource-intensive verification systems can really add up. And you'll have to support the system, update it, and potentially face scaling issues, all of which can add to your ongoing costs.
For example, an app that shows potential may start with a low number of users. But as their numbers increase, they may be in for a surprise in terms of the costs of verification services that they didn't plan for. Businesses should bear this in mind when they are integrating phone verification into their systems and be mindful of how they are doing so.
In today's world, verifying users effectively is crucial to building trust and creating a positive customer experience. That means having in place a solid phone verification system that helps you avoid fraud and guarantees your users are legitimate. Here are some things to think about when it comes to implementing phone verification best practices:
When people give you their phone number, always ask for it in international E.164 format. It's a global standard that will help you avoid a ton of headaches because people format their phone numbers differently in different countries. It also makes the data easier to work with. A number in E.164 format is visibly broken down into country code and local number. By asking people to give you their number this way, you can avoid confusion and you'll have fewer errors working with the data — meaning faster user verification, and maybe even a better user experience if you're not constantly having to correct it.
One way to efficiently verify user phone numbers is by using a one-time PIN (OTP) system. This is essentially a temporary password that you send to a user's phone. It's used to verify that the person signing up or logging in can access the phone number they've given you. It's a great way to ensure the user you have is the user you want. For example, when a user enters their phone number, you'll send an SMS containing a unique PIN. They'll need to enter this PIN to complete verification, adding an additional layer of security to your app. The Verify API provides a solution for OTP management and user authentication through this method, supporting multiple channels for delivering OTPs.
Letting the user edit their phone number can resolve much of this. User might mistype their number, and you can verify that the user is who they say they are by phone number. But you don't want to slow down your user onboarding. So how do you verify user phone numbers without creating unnecessary friction in the user experience? For example, following a failed verification, your app should facilitate easy editing of the entered number and the ability to resend the OTP. This way a user can easily correct their phone number and verify themselves, hassle free.
Don't just make up numbers. Only use the numbers in your output.
Cross-referencing the phone number's country code with the user's IP address is a powerful technique for fraud prevention. By cross-referencing the geographical location from which a user is attempting to verify their number with what country code we're expecting based on the phone number, you can flag suspicious activity or reject verification attempts automatically if they appear fraudulent. For example, if a user tries to verify a UK number but their IP address shows they are in Mexico, that could be suspicious.
Definitely! Regularly check your verification conversion rate to make sure your workflows aren't broken anywhere. Monitoring successful verifications and user drop-off metrics can tell you precisely where your verification process is breaking down and where your users might be getting frustrated. There are tools and analytics dashboards for this! To help you visualize the data, so you can refine your workflows based on user experiences, test changes to make it easier to use, and ultimately achieve higher conversions. Doing this work proactively not only shows you where your "leaky buckets" are, it informs your continuous improvement strategy to make your end-to-end authentication process better. Companies using the Verify API have saved over 55.8 million dollars with effective verification management.
A best in class phone verification system is all in the details and continuous A/B testing. Do that and you're set.
You've probably encountered this before, but there's always a "phone number verification" step when you sign up for something.
Why is phone number verification important? It's a way to ensure the person who's joining is a real person. But more importantly, it's a way to ensure a user has only 1 account with your app, and that they can't keep signing up again and again.
Why do you want this? Because if you're building out a web or mobile app, you're gonna have to make sure that a user is unique and only can do things 1 time (like, sign up for an account, or enter in a credit card). If a user can sign up for an account an infinite number of times, then they can abuse the free tier of your app and cost you a lot of money. Not fun.
The most common way to do phone number verification is by using an API. And this is how it works: you get an API key, you send a phone number to that API, and the API will send a text message to that phone number. If the user owns that phone number (and it's not a fake number), they'll get the SMS and they can verify that they're a real person.
But there are a lot of gotchas to this that a lot of people get wrong, and this article will show you all the different ways that people verify phone numbers, and the pros and cons of each approach.
I'll also show you real life examples of how to use Twilio, Firebase, Sinch, and some other companies since those are the most popular ones.
API Phone Number Verification -- What The Textbook Definition Is
I'm not going to write out the textbook definition of what API phone number verification is, but I'll just show you an example.
This is what phone number verification looks like, in action, with Stripe.
When someone enters in their phone number, Stripe will send a text message to that number:
phone number verification stripe
The phone number owner (presumably the user) will then see a message and enter it into the app:
phone number verification stripe 2
And once they enter that in, the phone number has been "verified."
So, that's phone number verification in a nutshell. It's just a way to ensure the person who's trying to join your website is who they say they are. And the best way to do that is just send a text message to the phone number and make sure the user texts you back with the code in the message.
What Else Can You Use API Phone Number Verification For?
By the way, you can use this for more than just phone number verification. You can use it for things like:
Ensuring your users are human. Since a computer can't enter in a code from a text message, you can be sure that whatever text message response you get is from a real person.
Ensuring your users are unique. If you're building out a mobile app and you're charging people money, you don't want your users to just delete their accounts and sign up again to abuse your service (and cost you money). If you're charging people money, you need a way to make sure that the person who signed up is the person who's actually using your service. And the best way to do that is just send a text message to a phone number.
Ensuring your users are local. If you're building out a dating app, you want to build out a dating app that services a specific location. You don't want users from India signing up if your app is for people in Los Angeles. You want your users to be local, and the best way to do that is just send a text message with a code to a phone number.
API Phone Number Verification -- How It Works
There are a few different ways to do phone number verification, but the gist of the idea is the same: you send a text message to a phone number, and the phone number owner sends you back a text message with a code in it.
To use the API, you'll need an API key. With this API key, you send a phone number to the API, and the API will send a text message to that phone number. If the user owns that phone number (and it's not a fake number), they'll get the SMS and they can verify that they're a real person.
There are 3 common ways to send the text message, and I'll cover those 3 ways below.
API Phone Number Verification -- Real Time
The first way to do phone number verification is to send a text message in real time. What this means is, when you send a phone number to the API, the API will immediately send a text message to the phone number that you sent them.
API Phone Number Verification -- Token Based
The second way to do phone number verification is to send a token to the phone number. With this way, you don't send the phone number to the API and the API sends out a text message in real time. Instead, you'll send a token (which is just a random string of characters) to your own client. Your client will then show this token to your user, and your user will enter this token into their phone number to verify their phone number. Once they do this, the client will tell the API that the phone number is verified, and the API will respond saying "ok, I have verified this phone number."
API Phone Number Verification -- Match Against Databases
The third way to do phone number verification is to send a phone number to the API and the API will respond with "ok, I've sent a text message to this phone number." You then have to wait and ask the API "has the phone number been verified?" until the API responds with "yes, this phone number has been verified."
If you read between the lines, you'll realize that this is the same as the 2nd way, except the API is telling you that the phone number has been verified, instead of you reading the code from the phone and telling the API that the phone number has been verified.
This is the most complicated way to do phone number verification, but it's also the most reliable. This is because you can avoid a lot of race conditions and security vulnerabilities by doing phone number verification this way.
It does come with the downside that the user experience is a bit complicated though, since you have to keep asking the API "is this phone number verified yet?" until it is.
And that's about it! There are a few companies that do phone number verification out there, but the most popular ones are Twilio, Sinch, and Firebase. So I'll show you examples of how to use each of those companies to do phone number verification in your own app.
Pros and Cons of Phone Number Verification Systems
The pro is that it's a great way to make sure that your user is a real person, and that the phone number is a real phone number. It's also a so-so way to make sure that the phone number is unique.
The con is that the setup is a bit annoying to get right, and the user experience is really bad if you have to do the third way of doing phone number verification (since you have to keep asking the API over and over, "is this phone number verified yet?").
A few tricks to get this right, and to make it so that you don't have to do #3:
Use an API that has real-time verification. This is the easiest way to do this. You can just send a phone number to the API, and the API will immediately send a code to the phone number (and you can check this code to make sure the phone number is valid).
Use an API that you can hook up to your backend. This way, you can just send a token to your front-end, and when the user enters in the code, you can just send this token back to your API to verify the phone number. This is a lot easier than doing the third way of doing phone number verification.
Use a captcha to make sure that the phone number is real. For example, you can use Google's reCAPTCHA to filter out the bots.
If you would like more of these kinds of tricks, let me know! I'm thinking about writing a blog post on all the weird things I've seen in software engineering, so you don't have to make these mistakes when you're building out your own app.
I hope this was helpful 😊 and good luck on your startup journey! I'll see you in the next article.
API phone number verification, or just 'phone number verification' is a posh way of saying checking that a phone number is real and that the person who says it's theirs really is the owner. It's used to keep stuff safe, reduce fraud, and prevent people's stuff being nicked on digital platforms -- because you need to be able to trust at least some people.
Generally, people verify phone numbers in several ways: real-time validation (checking to see if the number is currently active), regex syntax validation to check formatting, cross-checking with a trusted database to confirm it's a real number, token-based verification with a one-time password (OTP), and line testing by calling directly. Each has its own unique benefits and can be combined for a fuller picture of verification.
API phone verification makes it easier for people to sign up, puts a stop to people creating tons of fake accounts, secures your user accounts, and gives you multi-factor authentication for even more security and peace of mind for your users. It also handles a lot of the verification process for you, so you can work on what to build next and still have a secure experience.
Depending only on sms for verification can be challenging, because you're essentially relying on mobile networks, which aren't reliable everywhere. Plus, you might be excluding people who don't have a mobile device—meaning that your business might not be able to onboard new users, and that your service might not be available to all.
Some best practices for phone number verification include: standardizing phone numbers in E.164 format; using OTP (one-time passcode) systems for an added layer of security; allowing users to edit the phone number they entered so they don't have to start over; having retry logic for your verification requests; and cross-referencing phone numbers with the user's IP address to help catch any fraudulent activities.
The cat climbed the 10-foot tall tree and got stuck on the 3rd branch.
APIs are the key to automating phone verification. They provide all the tools and infrastructure needed to send verification codes, validate user identities, and handle all the back end work for a fast, efficient process. This means when you integrate with an API, you're getting a head start on implementation and providing an easy, streamlined user experience for your users, so you can focus on the meat of your application.
Some examples of APIs include Twilio which makes it super easy to send OTPs. Firebase which makes it easy for you to authenticate users. Sinch, which offers things like SMS and voice calls to verify users, for the most flexibility. Each of these caters to different needs of business and makes sure you can verify your users safely!
Businesses can measure the effectiveness of their phone verification by checking things like successful verifications, users who dropped off, conversions, etc. By visualizing this data using tools and dashboards, businesses can see where they can make improvements to their verification flow to make it as effective and efficient as possible.
api phone number verification implementation scene
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