SMS Login: User Guide for Sponsors

Section A: What is an SMS login?

SMS login is an authentication method where a system sends a unique, time-limited code to a user’s mobile device via text message to verify their identity. It can operate either as part of a two-step process alongside a password or as a standalone passwordless method. Organisations adopt SMS login because it requires minimal setup, works on virtually any mobile phone and leverages a communication channel users already understand. However, its ease of use must be balanced against its recognised security weaknesses.

In the context of the UK Sponsor Management System (SMS), used by Home Office-licensed sponsors to manage their sponsor licence and sponsored workers, SMS login forms part of the secure authentication measures required for key personnel to access the system. As the SMS contains sensitive immigration and compliance data, the Home Office uses SMS one-time passcodes as an additional verification layer to reduce the risk of unauthorised access.

1. Purpose

SMS login involves sending a one-time passcode (OTP) to a registered mobile number whenever a user attempts to sign in. The OTP is entered into the login interface, confirming that the person attempting to access the account has access to the mobile number on record. The primary purpose is to strengthen authentication beyond just a password, thereby reducing the likelihood of unauthorised access from stolen or guessed credentials.

For sponsor licence holders, the registered number must belong to the relevant authorised user as recorded in the Sponsor Management System. If this number changes, it must be updated promptly in the system to avoid being locked out. The Home Office will only send the OTP to the number recorded in the SMS account profile, which is why keeping personnel details accurate is a key compliance requirement.

2. Common Implementation Models

Each model offers a different balance between convenience and security. Password + SMS OTP is the most common and is the model used by the UK Sponsor Management System. Passwordless SMS login is typically seen in consumer applications prioritising ease of access. In high-security systems like the SMS, OTPs are time-limited and may expire in under 5 minutes, meaning users need to be ready to receive and input the code quickly.

In the password plus SMS OTP model, users enter their usual login credentials, followed by an OTP sent by SMS, adding a second factor for authentication. In the SMS-only or passwordless model, the user enters their registered phone number and is granted access after entering the SMS code. This removes the need for a password. In the SMS step-up authentication model, an OTP is triggered only for higher-risk transactions, such as financial transfers or changes to account security settings.

3. Examples of Use in Practice

In the UK, SMS login is used by online banking platforms to confirm transactions, e-commerce sites to verify purchases, and government digital services to validate access to accounts. Microsoft’s Entra ID allows organisations to configure SMS sign-in as a passwordless method for users without smartphones or authenticator apps. Retail loyalty schemes also employ SMS login to allow customers quick account access without remembering complex credentials.

For sponsor licence holders, SMS login is required every time a Level 1 or Level 2 user accesses the Sponsor Management System to assign a Certificate of Sponsorship (CoS), report a migrant worker’s change of circumstances, or update licence details. If the OTP is not received, the Home Office guidance advises checking that the registered mobile is switched on, has network coverage, and has not blocked automated messages. Persistent login issues may require contacting the Sponsorship, Employer and Education Helpline to restore access. Identity verification will be required before access is restored.

4. Practical Considerations for Sponsor Licence Holders

While SMS login is straightforward, sponsors should ensure:

• The registered mobile number for each SMS user is current and belongs to that user personally, not a shared device.
• Key personnel have network access and can receive messages when travelling abroad.
• There is at least one backup Level 1 user with active SMS login credentials to prevent operational disruption if the primary contact is unavailable.
• Any changes to mobile numbers are updated in the SMS immediately, as the Home Office will not send codes to unregistered numbers.

Failing to maintain accurate contact details can result in being locked out of the SMS, delaying mandatory reporting duties and potentially putting the organisation in breach of sponsor licence compliance requirements.

Section B: How to Log in to the SMS

SMS access is limited to authorised Level 1 and Level 2 users, and the process involves entering a username and password, followed by a one-time passcode (OTP) sent to your registered mobile number.

When a sponsor licence is first granted, the Home Office posts the initial user ID to the Authorising Officer and emails the password to the nominated Level 1 user. If an existing Level 1 user adds a new account, the password will be sent to the new user by email once the request is approved. These credentials are personal and must be kept secure at all times.

To log in, visit the official SMS login page and save it for future use. Avoid clicking through from unverified sources to reduce the risk of phishing. Enter your user ID and password exactly as issued, taking care with case sensitivity and avoiding extra spaces. The system will lock your account after three incorrect attempts. If this happens, you will need to wait at least 30 minutes before trying again.

On your first login, the system will prompt you to change the default password. The new password must be between 12 and 256 characters, include at least one uppercase letter, one lowercase letter, one number, and one special character, and must not contain spaces or include your username or user ID.

After the username and password are accepted, the system will send a one-time passcode to your registered mobile number. You must enter this code into the login page within the allowed time, usually less than five minutes. If the code expires or is entered incorrectly, you will need to restart the login process to receive a new one. The OTP is single-use and cannot be reused even if it has not expired. If the code does not arrive promptly, check that your phone is switched on, has a network signal, can receive automated text messages, and that the registered number in the SMS is correct.

Once you have successfully entered the OTP, Level 1 users will be directed to the message board and must read any communications from the Home Office before proceeding. Level 2 users will be taken directly to the functions allowed for their role. From the dashboard, users can carry out tasks such as assigning Certificates of Sponsorship, reporting changes to a worker’s details, updating licence information, or managing other users, depending on the permissions assigned to their account.

Note: Some options may be unavailable if the licence is suspended, expired or otherwise restricted.

To keep access uninterrupted, ensure all user and contact details remain accurate, including the registered mobile number. Appoint at least one backup Level 1 user with a different mobile number to avoid organisation-wide access issues. Test that OTPs are delivered successfully when changing mobile handsets or network providers, and aim to complete reporting well before deadlines in case of technical delays. Always log out properly after each session to protect account security.

If you encounter login problems, wait the full lockout period before trying again, double-check that your credentials and OTP are entered correctly, and confirm that your registered mobile number is able to receive UK text messages. If these checks do not resolve the issue, contact the Sponsorship, Employer and Education Helpline, but be aware that urgent issues may not be resolved immediately.

Section C: Benefits of SMS Login

Organisations adopt SMS login because it offers a practical balance between ease of deployment and user accessibility. It operates on standard mobile networks, meaning users do not need specialised devices or software to receive authentication codes. For many businesses, particularly those with a broad or non-technical user base, SMS login provides a workable security measure without creating significant barriers to account access.

In the UK Sponsor Management System context, SMS login is particularly effective for ensuring secure access by key personnel without the need for specialist technical knowledge or additional hardware. It allows Level 1 and Level 2 users, including those working remotely or across different sites, to access the system securely as long as they have a registered mobile number that can receive texts. This makes it a pragmatic solution for sponsor licence holders who must comply with Home Office security requirements while maintaining operational efficiency.

1. Broad Accessibility

SMS login works on virtually all mobile devices, from the latest smartphones to older handsets, provided they can receive text messages. This universality makes it suitable for organisations serving customers or employees who may not have access to app-based authentication or high-speed internet. It also eliminates the need for users to install additional tools, which can be a barrier in certain demographics or regions.

For sponsor licence holders, this means that key personnel travelling internationally can still log into the SMS provided they have mobile network coverage and their number can receive UK-originating text messages. This is particularly useful in urgent situations, such as reporting a migrant worker’s change of employment status within the strict Home Office deadlines. However, sponsors should be aware that in some countries, SMS delivery from UK systems may be delayed or blocked, which reinforces the need for backup authorised users.

2. Minimal Setup Requirements

Simple onboarding means registration usually involves providing a mobile number, which can be validated instantly with a test code. Rapid implementation allows organisations to enable SMS login without extensive infrastructure changes, while no specialised hardware is required, meaning users do not need security tokens, biometric scanners or other dedicated devices.

This low barrier to entry means businesses can roll out SMS login quickly, even to large, geographically dispersed user bases. For the Sponsor Management System, this means new Level 1 or Level 2 users can be onboarded and made operational almost immediately once their account is created and their mobile number is verified. This reduces downtime when personnel changes occur and ensures the organisation can continue meeting sponsor licence duties without interruption.

3. Familiar User Experience

Most users are accustomed to receiving text messages and understand how to retrieve and enter a code. This reduces training requirements and minimises support requests. For time-sensitive access, such as approving transactions or signing into a service from a new device, SMS login offers a familiar and straightforward interaction.

In the sponsor licence context, the familiarity of SMS login reduces the likelihood of login errors that could delay important actions, such as assigning a Certificate of Sponsorship to a candidate with a job start date approaching. Since sponsor compliance often involves strict timeframes, a login process that requires little or no training helps avoid missed reporting deadlines and the compliance risks that follow.

4. Practical Benefits for Sponsor Licence Holders

For organisations using the UK Sponsor Management System, SMS login provides:

• Consistent access for users across different locations and devices without additional software installations.
• A secure method that meets Home Office requirements without complex IT setup.
• Fast onboarding of new key personnel, minimising gaps in compliance coverage.
• Reduced dependency on IT support for day-to-day system access.

These benefits, combined with its low cost and ease of adoption, make SMS login a practical authentication tool for maintaining sponsor licence compliance in line with Home Office standards.

Section D: Risks and Vulnerabilities of SMS Login

While SMS login improves security over password-only access, it is not immune to compromise. The reliance on mobile networks introduces risks that are not present in app-based or hardware-based authentication methods. Criminals can exploit weaknesses in telecommunications infrastructure, as well as human factors, to intercept or bypass the one-time passcode process. Understanding these risks is essential for organisations that use or are considering SMS login.

For UK Sponsor Management System (SMS) users, these vulnerabilities carry compliance implications. If an unauthorised person gains access to a sponsor’s SMS account, they could alter sponsor records, withdraw Certificates of Sponsorship, or make false reports to the Home Office. Such activity could lead to an immediate compliance investigation, suspension, or revocation of the licence.

1. SIM Swapping and Number Porting Fraud

SIM swapping occurs when an attacker convinces a mobile network provider to transfer a victim’s phone number to a new SIM card under the attacker’s control. This enables the attacker to receive all incoming calls and messages, including authentication codes. Criminals often use social engineering, stolen personal data, or insider cooperation to execute the swap. Once successful, they can bypass SMS login entirely by entering the stolen code.

For sponsor licence holders, this means a malicious actor could gain full control of the Sponsor Management System account linked to that number. As mobile providers do not automatically detect or block fraudulent SIM swaps, sponsors should encourage key personnel to set up additional security with their network provider, such as a PIN or passphrase for number transfer requests.

2. Interception Through SS7 Vulnerabilities

The SS7 protocol weakness refers to flaws in the Signalling System No. 7 protocol, used globally to route calls and messages, that allow sophisticated attackers to intercept SMS messages. Exploitation by criminal networks occurs when attackers take advantage of these flaws remotely without physical access to the victim’s phone.

Although such attacks are less common than SIM swaps, they are well-documented and pose a serious risk for high-value targets. Sponsor Management System accounts qualify as high-value because they provide direct access to government-controlled immigration records and the ability to issue sponsorship. Sponsors should treat all OTPs as sensitive data and avoid reusing numbers already compromised in previous breaches.

3. Phishing and Social Engineering Attacks

Attackers can trick users into revealing their SMS codes by posing as legitimate service providers. This can occur through fraudulent websites, emails, or phone calls. Once the code is disclosed, the attacker can complete the login process before it expires. Unlike some app-based authentication methods, SMS OTPs provide no context about the login attempt, making users more susceptible to deception.

In a sponsor licence context, phishing attempts may be disguised as urgent Home Office messages about licence renewal, migrant worker status changes, or compliance audits. Key personnel should be trained never to share OTPs verbally, via email, or through links, and to verify any unexpected communication through official Home Office contact channels.

4. Device Theft and SMS Sync Exposure

If a device is stolen while unlocked, an attacker can read incoming messages directly. In addition, SMS messages can be synced to other devices via cloud services, creating additional interception points if those accounts are compromised.

Sponsor licence holders should ensure that all authorised SMS users secure their devices with strong passwords or biometrics and review cloud backup settings to limit OTP visibility on secondary devices. If a registered device is lost or stolen, the number should be removed from the SMS account immediately and replaced with a secure alternative.

5. Practical Risk Mitigation for Sponsor Licence Holders

All SMS users should put account-level security measures in place with their mobile provider to help guard against unauthorised SIM swaps. Sponsors should also keep a backup Level 1 user account that is linked to a separate mobile number so access can be maintained if the primary number is compromised. Key personnel must be trained to recognise phishing attempts, particularly those that appear to come from the Home Office. Any change in mobile number, whether due to loss of the device, a number change or suspected compromise, must be updated in the SMS immediately. Taking these steps protects system access and significantly reduces the likelihood of a breach that could result in a Home Office compliance review.

Section E: Best Practices for Using SMS Login Securely

Although SMS login has recognised vulnerabilities, its security can be strengthened through a combination of technical controls and user education. Organisations that continue to use SMS authentication should ensure that both their infrastructure and their users are protected against known attack methods.

For UK Sponsor Management System users, applying these measures is not only about protecting account access but also about safeguarding immigration data and preventing compliance breaches. A compromise of SMS credentials could lead to unauthorised changes to licence details, fraudulent Certificates of Sponsorship being issued, or missed statutory reporting deadlines — all of which carry serious consequences under Home Office sponsor guidance.

1. Combine SMS with Additional Factors

SMS should be one element of a multi-factor authentication strategy rather than the sole verification step. Pairing SMS OTPs with a password, biometric verification, or an authenticator app code increases the difficulty for attackers. For high-value accounts, requiring a hardware security key in addition to SMS further strengthens security.

In the sponsor licence context, although the Home Office currently mandates SMS OTP as part of its secure login process, organisations can apply internal security protocols requiring an extra verification step before authorising high-impact actions, such as assigning a Certificate of Sponsorship or updating key personnel details.

2. Harden the User Verification Process

These measures make it more difficult for an attacker to exploit a stolen or intercepted code:

• Limit OTP Validity – Keep code expiry times short to reduce the window for interception.
• Restrict Login Attempts – Implement lockouts after repeated failed OTP submissions to block brute-force attempts.
• Monitor for Suspicious Activity – Detect abnormal login patterns, such as logins from new locations immediately after SIM changes.

In the UK Sponsor Management System, account lockouts following multiple failed OTP entries can be time-consuming to resolve, as the Home Office will require identity verification before restoring access. Sponsors should therefore balance security with the operational need to avoid unnecessary downtime.

3. Educate Users on Security Risks

User awareness is a critical defence. Training should include recognising phishing attempts, understanding the risks of sharing codes, and securing devices with strong passcodes or biometric locks. Users should also be encouraged to contact their mobile provider immediately if they suspect unauthorised SIM activity.

For sponsor licence holders, induction and refresher training for Level 1 and Level 2 users should cover real-world threats such as fake Home Office messages requesting OTPs, SIM swap scams, and the dangers of accessing the Sponsor Management System over unsecured public Wi-Fi networks.

4. Secure Mobile Network and Account Links

Where possible, work with telecom providers to add security layers such as SIM swap verification, account PINs, or port-out protection. Organisations can also prompt users to enable these protections on their mobile accounts to reduce the risk of number takeover.

For sponsor licence purposes, key personnel should register their mobile numbers with providers that offer strong anti-fraud measures, especially if they regularly access the SMS from abroad. Mobile account security settings should be reviewed at least annually as part of internal sponsor compliance audits.

5. Maintain Backup Access Plans

Sponsors should ensure they have more than one active Level 1 user with a separate mobile number registered in the SMS. This ensures that if one user’s mobile number is compromised, changed, or unavailable, another authorised person can access the system to fulfil urgent reporting duties and prevent compliance breaches.

Section F: Alternatives to SMS Login

Organisations concerned about the vulnerabilities of SMS login can strengthen account security by adopting more secure authentication methods. Modern alternatives often provide better resistance to interception and social engineering while maintaining user convenience. The right choice depends on the level of protection required, the user base’s technical capabilities, and the systems being secured.

For UK Sponsor Management System (SMS) users, any alternative authentication method must be compatible with Home Office systems. Currently, the Sponsor Management System requires SMS OTP for login, but organisations can apply additional internal security layers alongside the mandated process. This can include secondary verification steps before authorising high-impact changes to sponsorship records or issuing Certificates of Sponsorship.

1. Authenticator Applications

Authenticator apps, such as Google Authenticator or Microsoft Authenticator, generate time-based one-time passcodes on a user’s device without relying on mobile network delivery. Codes are stored locally and are typically valid for 30 seconds, making them resistant to interception. Many apps also support push-based verification, where the user simply approves or denies the login attempt within the app interface.

For sponsor licence holders, authenticator apps can be used internally as an extra verification layer for sensitive actions within the organisation. For example, before an internal system administrator allows a Level 1 user to log into the SMS, they could require an app-based code as well as the Home Office-issued SMS OTP. This helps reduce the risk that a compromised OTP alone could allow unauthorised access.

2. Hardware Security Keys

Hardware security keys provide one of the highest levels of protection, though they require an upfront investment and user training. In a sponsor licence environment, they can be issued to key personnel as part of an internal security policy, ensuring that only authorised staff with both the hardware key and the registered mobile number can approve changes to sensitive sponsorship data.

• FIDO2 and U2F Devices – Physical keys like YubiKey or Titan Security Key that require the user to physically connect or tap the device during login.
• Strong Phishing Resistance – Hardware keys validate the domain before sending credentials, reducing the risk of credential theft through fake websites.

3. Biometric Authentication

Biometrics such as fingerprint scanning, facial recognition, or voice authentication can replace or supplement traditional logins. When stored and processed securely, biometric data offers strong assurance that the person attempting access is the authorised user. However, organisations must ensure compliance with data protection laws, including the UK GDPR, when handling biometric data.

For sponsor licence holders, biometrics can be used to secure the devices from which the SMS is accessed. Requiring biometric unlock before opening the browser session for the Sponsor Management System adds a security barrier that prevents unauthorised access if the device is lost or stolen.

4. Push Notification Approval

Push-based authentication sends a secure login prompt to a registered device via an encrypted app connection. The user verifies the attempt by tapping “approve” or “deny” without needing to enter a code. This method reduces phishing exposure and can be combined with device-based risk analysis.

In the sponsor licence context, push notification approval could be integrated into internal approval workflows. For example, before a CoS is assigned, a push approval could be sent to a compliance manager’s device to confirm the action, even though the Home Office SMS login itself still uses SMS OTP.

5. Internal Multi-Layered Security Approach

Since the Sponsor Management System does not currently allow alternatives to SMS OTP for login, sponsors seeking stronger protection should implement internal security controls, such as:

• Requiring secondary approval from another authorised user for high-risk actions in the SMS.
• Securing devices with biometrics or hardware keys before logging into the SMS.
• Maintaining a whitelist of approved devices and networks for accessing the SMS.

This layered approach ensures that even if an attacker bypasses the SMS OTP step, they cannot complete critical actions without passing additional internal checks.

Section G: Role of SMS in Sponsor Licence Compliance

For UK sponsor licence holders, the Sponsor Management System (SMS) is the Home Office’s online platform for managing sponsored workers and fulfilling ongoing compliance duties. Access to and proper use of the SMS is not optional — it is a mandatory element of licence management. Failing to use the SMS correctly, or neglecting to record and report required information, can lead to compliance action that jeopardises the licence.

The SMS is central to the Home Office’s sponsorship regime because it is the primary mechanism through which sponsors demonstrate that they meet their ongoing duties. All updates, reports, and changes made in the SMS are visible to UKVI and may be reviewed during compliance audits or investigations. This means that the integrity of the data in the system is as important as the timeliness of its submission.

1. SMS as the Core Licence Management Tool

The SMS allows authorised users within a sponsoring organisation to carry out functions such as assigning Certificates of Sponsorship (CoS), reporting worker changes, updating key personnel details, and managing licence renewals. The Home Office uses data submitted through the system to monitor sponsor activity and ensure compliance with immigration rules. Access is role-based, with Key Personnel such as Level 1 and Level 2 users responsible for day-to-day operation.

From a compliance standpoint, the SMS is not just an administrative portal — it is a legally significant system of record. Every action taken, from assigning a CoS to updating a job location, is logged and may be referenced in enforcement proceedings. This means sponsors must ensure that only trained and authorised personnel have access, and that all actions in the SMS are supported by verifiable evidence kept on file in accordance with Appendix D record-keeping rules.

2. Compliance Duties Linked to SMS Use

• Accurate Record-Keeping – All worker records entered in the SMS must match supporting documentation held on file, such as passport details and employment contracts. Discrepancies can raise compliance concerns during a Home Office audit.
• Timely Reporting – Sponsors must report changes in a worker’s circumstances within strict deadlines, usually 10 working days, including changes to job title, duties, salary, work location, or early termination of employment.
• Licence Detail Maintenance – Any changes to the organisation’s structure, address, or Key Personnel must be updated in the SMS promptly to avoid data discrepancies that may suggest mismanagement or concealment of information.

Meeting these duties ensures the Home Office has up-to-date information for compliance monitoring and reduces the likelihood of audit failures. It also provides a defensible position for the sponsor if the Home Office queries an action or decision.

3. Risks and Penalties for Non-Compliance

Failure to use the SMS correctly can result in sanctions ranging from an official warning to full licence revocation. Common breaches include delayed or missed reporting of changes, entering inaccurate data, and allowing unauthorised users to access the system.

Penalties for non-compliance can include:

• Licence Downgrading – Reduction from an A-rating to a B-rating, requiring a time-limited action plan at the sponsor’s expense. During this period, the sponsor’s ability to issue new CoS may be limited.
• Licence Suspension – Temporary removal of the ability to assign new CoS while the Home Office investigates compliance concerns. Suspension is often accompanied by reputational damage and operational disruption.
• Licence Revocation – Permanent loss of sponsorship rights, with immediate impact on current sponsored workers’ immigration status. Workers may have their leave curtailed, and the organisation may be barred from reapplying for a set period.

In serious cases, non-compliance may also lead to civil penalties or prosecution under immigration law, especially where false statements, fraudulent documents, or deliberate non-reporting are found. A compromised SMS login, whether through poor security or shared credentials, can also trigger a compliance investigation.

4. Best Practice for SMS Management

Sponsors should allocate SMS access only to trained staff who understand both the technical and legal aspects of the system. Regular internal audits of SMS data against HR records help identify and correct errors before they attract Home Office scrutiny.

Practical best practices include:

• Setting up calendar reminders for all reporting deadlines, ensuring no update is missed within the 10 working day window.
• Maintaining full evidence for every action taken in the SMS, stored in line with Appendix D retention rules.
• Reviewing and updating key personnel and contact details regularly to avoid login delays or security breaches.
• Applying secure login practices, such as never sharing credentials and ensuring registered mobile numbers for SMS OTP are current and accessible.

These measures not only help avoid technical lockouts but also demonstrate to the Home Office that the organisation takes its sponsor duties seriously, which can be important if the licence is ever reviewed or challenged.

Section H: Summary

SMS login remains a widely adopted authentication method because it is easy to implement, accessible on almost any mobile device, and familiar to users. It can serve as either a standalone sign-in method or as part of a layered security process. However, its security depends heavily on correct implementation and awareness of its vulnerabilities. Risks such as SIM swapping, SS7 protocol interception, phishing, and device theft highlight the need for supplementary safeguards.

For organisations, SMS login can play a valuable role in securing accounts where user convenience is a priority, but it should not be the sole method for protecting high-value or sensitive systems. Pairing SMS with additional authentication factors, enforcing short code validity periods, monitoring for suspicious behaviour, and educating users on phishing and mobile account security can significantly improve its resilience.

In the long term, businesses should evaluate more secure alternatives such as authenticator apps, hardware security keys, biometrics, or push-based authentication to mitigate the inherent weaknesses of SMS.

Section I: FAQs

Is SMS login secure enough for online banking?

SMS login offers more security than password-only access, but it has known weaknesses such as SIM swapping and interception risks. Most banks use SMS as part of a multi-factor authentication process rather than as the sole security measure.

How long should an SMS one-time passcode remain valid?

Best practice is to set OTP validity between 30 seconds and 5 minutes. Shorter expiry times reduce the window for interception while still allowing legitimate users enough time to enter the code.

Can an attacker access my account if they steal my phone?

If the device is unlocked or if messages are synced to another compromised device, an attacker could intercept SMS codes. Strong device security settings and remote wipe capabilities can help mitigate this risk.

What should I do if I suspect a SIM swap?

Contact your mobile network provider immediately to block unauthorised access. You should also change account passwords, remove SMS login where possible, and monitor accounts for suspicious activity.

Are there more secure alternatives to SMS login?

Yes. Authenticator apps, hardware security keys, push notifications, and biometric authentication offer stronger protection by removing reliance on mobile networks and reducing the risk of interception.

Section J: Glossary

Section K: Additional Resources and Links