Asking for an identity check
Sending requests
You can require a recipient to enter a one-time code before they sign, sent either to their email address or to their mobile number.
Choosing a method
Email is available wherever mail is configured. A text message needs a mobile number on the recipient, and a request will refuse to send if you have asked for one without it — a code that cannot be delivered would leave that person unable to sign at all.
What the record says
The certificate reports the check that was actually enforced, not the one configured at the time you read it. Raising somebody's requirement after they have signed does not change what their certificate says about them, because it did not change what they did.