7 Methods to Verify the Identity of Your Callers

As annoying as it can be for customers to prove who they are sometimes, verifying identity over the phone is crucial. In fact, it might be the single most important thing your contact centre does!

Getting it wrong can lead to serious problems like fraud, data breaches, and a complete erosion of customer trust.

With scams becoming more sophisticated, verifying who’s on the other end of the line is no longer just a box to tick – it’s a critical step you must complete every time to safeguard your business, protect your customers, and maintain your company’s reputation.

So, here’s some advice on how to get it right – in ways that protect all involved, whilst keeping the process smooth, respectful, and secure.

1. App-Based or Secure Messaging Channel Verification

If a customer calls from within your app (e.g. via a secure call or chat button), they’ve already been authenticated through the app’s login process – often using biometrics like fingerprint or face ID. This gives you a high level of certainty that the user is who they say they are.

WhatsApp and other secure messaging platforms can also be used for initial contact, where two-factor authentication (2FA) or in-app verification links can be sent before speaking live.

Best used when: Your audience is mobile-savvy and you want to combine customer service with streamlined, app-based access.

2. Single Verification Across Channels (No Repeats!)

Let’s say a customer passes verification in the IVR or with an agent, and then gets transferred to another department.

Rather than making them repeat the same process, your systems store a “verified” status or token that carries over – so other agents know the identity check has already been completed.

This can be done using CRM flags, call tracking metadata, or integrated case management systems.

Best used when: You want to create a seamless, joined-up customer journey – especially for more complex or multi-step enquiries.

3. Manual Verification via Agent-Led Questions

With this method, a human agent asks the caller a set of predefined security questions. These are usually based on:

• Personal details (postcode, date of birth)
• Known transactions or account activity
• Memorable word or secret question

Good agents are trained to spot hesitation, inconsistent answers, or signs of deception – and to escalate suspicious calls accordingly.

Best used when: You want a cost-effective, tried-and-tested method – but you’ll need strong agent training and policies in place.

4. AI-Powered Call Routing and Voice Biometrics

AI-powered contact centre systems such as Amazon Connect and Talkdesk use advanced technologies to enhance both call routing and caller verification.

For instance, Amazon Connect can analyse conversations in real time by picking up on sentiment, keywords, and compliance triggers.

Talkdesk, on the other hand, uses predictive routing to match callers with the most suitable agents based on past interactions and context.

Some of these systems also incorporate voice biometrics, analysing unique vocal traits like tone, cadence, and speech patterns. In some cases, the caller’s voice is compared to a stored “voiceprint” to verify their identity automatically.

Others focus on behavioural cues – such as hesitation, inconsistent answers, or signs of stress – and flag suspicious calls for further investigation.

Best used when: You have the budget and scale to support AI, and want to future-proof your security process.

5. One-Time Passcodes (OTPs) and Secure Links

When customers are required to use a one-time passcode, it is sent to their registered mobile or email. The caller must read this code back or enter it into the system to proceed.

In other cases, a secure link is sent (e.g. for ID verification or account updates), which expires after a short time and can only be accessed by the intended recipient.

Best used when: You need an extra layer of protection for account changes, payments, or access requests – especially over phone or digital channels.

6. Automated Checks via IVR (Interactive Voice Response)

An interactive voice response (IVR) is an automated phone system that interacts with callers using voice prompts or keypad inputs, often used to collect information (like account numbers or dates of birth) before the caller is connected to a live agent.

When a caller first connects, the IVR system asks them to input identifying information – usually via the keypad or speech recognition.

This could include things like:

• Date of birth
• Account number
• Last digits of a payment method
• A PIN or memorable word

Advanced IVRs can even perform initial checks before a human gets involved, verifying against the customer record in your CRM or database.

Best used when: You want a frictionless, front-loaded way to handle large call volumes while reducing agent workload.

7. CRM-Integrated Verification

If you have a customer relationship management (CRM) system, you can use it to automatically pull up a caller’s details – like their name, account history, and previous interactions – based on their phone number or ID input.

This allows agents to verify the caller more quickly and accurately, without relying on long lists of security questions.

When a call comes in, your telephone system pulls up the customer’s profile in your CRM using the incoming number (caller ID), IVR input, or a secure code. Agents can then verify the caller using known data – for example:

• Recent purchase history
• Past service interactions
• Registered address or email

This allows for more tailored, confident questioning and faster authentication.

Best used when: You want to empower agents to make quicker, smarter decisions without relying solely on scripted security questions.

Fraud Is Getting Smarter by the Day

The goal of caller identity verification isn’t to trip customers up or make life harder – it’s to protect them (and you) in a world where fraud is getting smarter by the day.

The key is to find your perfect blend of human judgement and technology, including:

• One-and-done – Verify once and carry it through the journey
• Fit-for-purpose – Use what’s practical for your size, team, and customer base
• Proactive, not paranoid – Stay ahead of threats without punishing honest callers

Done right, verification becomes a quiet strength in your service experience – one that builds trust, loyalty, and confidence every time a customer calls.

If you are looking for more information and advice on improving contact centre security, read these articles next:

• 5 Examples of Contact Centre Fraud – and How to Prevent Them!
• Top Call Centre Security Challenges and How to Fix Them

Reviewed by: Jo Robinson