Passkeys and Biometrics Are Not Universal Yet
The security community has been heralding the death of SMS-based verification for years, pointing to passkeys, hardware tokens, and biometric authenticators as superior alternatives. While these technologies have made impressive strides, adoption remains uneven across demographics, devices, and regions. As of early 2026, passkey support is still limited on older Android devices, budget smartphones, and many enterprise-managed environments.
Biometric authentication requires specific hardware capabilities that a significant portion of the global device fleet simply does not have. Fingerprint sensors and Face ID are standard on flagship phones, but hundreds of millions of users around the world rely on devices without these features. For any service that aims for broad accessibility, ignoring SMS means excluding a meaningful segment of the population.
The reality is that multi-factor authentication works best when it meets users where they are. Offering passkeys as a primary option while falling back to SMS ensures that security improvements do not come at the cost of user access. A layered approach remains the most pragmatic strategy for 2026.
SMS Is Ubiquitous: 7 Billion Mobile Subscriptions and Counting
There are now over seven billion mobile subscriptions worldwide, and virtually every one of them supports SMS messaging out of the box. No other second-factor channel comes close to this kind of reach. Email requires internet access and an account; authenticator apps require a smartphone and an app install; hardware tokens require a purchase and physical possession.
SMS works on every phone ever made, from the latest iPhone to a ten-year-old feature phone in a rural village. It requires zero configuration from the end user: no app download, no account setup, no QR code scanning. The verification code simply arrives in the messaging inbox that every phone user already knows how to use.
For businesses operating globally, this universality is not a convenience; it is a strategic necessity. When your onboarding flow needs to work for a banker in London and a farmer in rural India, SMS is the only verification channel that reliably reaches both.
No App Install Required
App fatigue is real. Users are increasingly reluctant to install yet another application, especially for a one-time verification step. Authenticator apps like Google Authenticator or Authy, while excellent for security-conscious users, add friction to the onboarding process that measurably reduces conversion rates.
SMS verification eliminates this barrier entirely. The user enters their phone number, receives a code, and types it in. The entire flow takes seconds and requires nothing beyond the device they already have in their hand. This simplicity translates directly into higher completion rates and lower drop-off during signup and login flows.
Studies consistently show that every additional step in an authentication flow costs between 5 and 15 percent of users. By using a channel that requires no setup, businesses preserve the frictionless experience that modern consumers expect.
Compliance Requirements in Finance and Healthcare
Regulatory frameworks in financial services and healthcare often mandate multi-factor authentication, and many explicitly recognize SMS as an acceptable second factor. PSD2 in Europe, RBI guidelines in India, and various state-level healthcare regulations in the United States all include provisions for SMS-based verification.
While some frameworks have begun encouraging stronger factors, the transition periods are long, and SMS remains compliant in the vast majority of jurisdictions. For companies navigating complex regulatory landscapes across multiple countries, SMS provides a consistently accepted baseline that satisfies auditors and regulators alike.
Abandoning SMS prematurely can actually create compliance gaps, especially in markets where alternative methods are not yet recognized by local regulators. The prudent approach is to support SMS alongside stronger factors, allowing organizations to meet the strictest requirements while maintaining broad accessibility.
Best Practices for SMS Verification in 2026
Implementing SMS verification well requires more than just sending a six-digit code. Modern best practices include using time-limited codes with a maximum validity of five minutes, rate limiting requests to prevent abuse, and implementing SIM swap detection to flag potentially compromised numbers before sending codes.
Message content matters too. Codes should be delivered with clear, concise messaging that includes the service name, the code, and an expiry notice. Including the domain in the message helps users identify legitimate requests and builds resistance to phishing attempts. Never include clickable links in verification SMS messages.
On the infrastructure side, multi-carrier routing with automatic failover ensures that codes reach users quickly regardless of their carrier or location. Monitoring delivery rates in real time and alerting on drops allows teams to catch and resolve issues before they impact significant numbers of users.
Finally, always give users the option to upgrade to stronger authentication methods. SMS should serve as the accessible baseline, with clear pathways to passkeys, authenticator apps, or hardware tokens for users who want additional security.