The tru.ID API verifies whether the SIM card associated with the phone number has recently changed, providing silent, continuous verification. SIM-based authentication is invisible to the user the check of the SIM happens in the background once the user inputs their mobile number. If your site or app already has the mobile phone number stored, even better – there’s no user action required at all. SIMCheck is recommended, having the additional benefit of being a quick, easy, and server-side integration.
Source: https://thehackernews.com/2021/07/how-to-access-mobile-carrier.html