How many minutes before verification code from sendVerificationCode expires?

I'm using Google Identity Toolkit's sendVerificationCode and verifyPhoneNumber to verify user's phone number. I have a timer to show when the code expires. But I can't find how many seconds/minutes before it expires.

sendVerificationCode only returns a string sessionInfo. I've already looked everywhere but can't seem to find any information on the expiry.

This is all they have on documentation

sendVerificationCode(body=*)
Send SMS verification code.

Args:
  body: object, The request body. (required)
    The object takes the form of:

{ # Request for Identitytoolkit-SendVerificationCode
    "recaptchaToken": "A String", # Recaptcha solution.
    "iosSecret": "A String", # Secret delivered to iOS app via APNS.
    "iosReceipt": "A String", # Receipt of successful app token validation with APNS.
    "phoneNumber": "A String", # The phone number to send the verification code to in E.164 format.
  }


Returns:
  An object of the form:

    { # Response for Identitytoolkit-SendVerificationCode
    "sessionInfo": "A String", # Encrypted session information
  }