SMS Login: Check if mobile number was used short time ago? (Feature Request)

We observed a problem with mobile phones automatically checking if they're connected to a hotspot and displaying the Captive Portal without having the user to open an Website: If the user navigates away to get the verification code sent to him, he cannot access the "enter the code" website again. Not shure if a cookie could be used to check if this user already requested a code - otherwise the FortiAuth may check if the phone number was used to send a code a short time ago and haven't completed the sequence - and allow the user to enter the code without requesting another one.