Check IMSI

Combat fraud and improve customer security with one simple solution

SIM swap fraud is a real threat to customers’ security, by enabling fraudsters to fool 2-factor authentication. By gathering information about a victim, criminals can impersonate them and order a fraudulent SIM card reissue, thereby gaining control over the phone number used for 2FA authorization. To alleviate this threat, GMS introduced the Check IMSI service

What is Check IMSI

Check IMSI prevents SIM swap fraud, strengthening your security

An International Mobile Subscriber Identity, or IMSI, is a unique code stored on and associated with the SIM card, not the mobile phone number (or MSISDN). If the phone number is transferred to a new SIM, for whatever reason, the IMSI is not. By comparing the number and the SIM card it is stored on, we can determine if someone is trying to intercept your customer’s communications.

How does it work

Before authorizing any interaction, the IMSI is requested from the SIM currently linked with the customer’s phone number, which GMS retrieves from the customer’s network operator. GMS then passes this to the client requesting this information, who can check whether or not the IMSI retrieved from the network is the same as that registered in their database.

If the two IMSIs do not match, the phone number has been swapped – transferred to another SIM, very possibly by someone looking to access the real customer’s finances. The enterprise can then contact the customer using some other channel (say email or a landline phone call) to verify their identity and alert them to a possible fraud.

All this happens in the background, without creating any extra steps or friction for the user.

Enhance customer security

Check IMSI from Global Message Services is another powerful tool in the cybersecurity arsenal, one that works in the background without the customer’s involvement and greatly complements 2FA.

At GMS, we immerse ourselves in your business and analyze your goals and audience. We jointly design the best communications solution for your specific needs and provide our infrastructure to implement it.

Enhance your company’s security today.

Get started



Our network encompasses 900+ mobile operators, with over 240 directly connected to GMS, which grants instant message delivery to any place on Earth


GMS’ multichannel messaging platform grants you access to multiple communication channels, which can be used depending on your business needs

International recognition

GMS was the first SMS services provider in Ukraine and has grown to become a recognized international messaging provider

Global presence  

GMS has six offices located all over the globe, and an HQ in Baar, Switzerland, meaning wherever you are, GMS is there for you


GMS sets and follows high standards of security, recognized by ISO certifications

Success cases

More than 400 brands enhance their audience interaction with multichannel communications, voice and customer engagement tools from GMS

Let’s grow your business together

Contact us to find out how you can benefit from our expertise