How do I know whether TTS or SMS will be used?

tyntec’s 2FA API detects the number type (landline or mobile) and by default decides the delivery channel to send the OTP. For fixed (landline) numbers, tyntec will use a text-to-speech (TTS) call, while SMS is the primary delivery channel for mobile numbers.

This is set by parameter via with the following possible values:

  • AUTO (will use SMS in case of mobile number or voice/text-to-speech in case of landline)
  • SMS
  • VOICE (text-to-speech)

Because the 2FA API is a highly customizable product, you can overwrite this algorithm and choose the delivery channel independent of the number type. This, however, might impact the probability of successful verification.