Hello,
If you are asking about the GATE Application form, you can do the verification after submission of the form.  The Verification process is slow due to heavy rush on the website so it is taking the time 25 to 30 minutes to receive the OTP. You can log-in your account by login GOAPS and verify your e-mail and mobile number.
Don't panic and wait patiently and complete the verification process.
Good Luck!