Sms authentication in cnmaestro

Hi Forum
Our Client wants to use SMS authentication.
Kindly help explain how this works

Does the explanation in the user guide help at all?

SMS Authentication section of the User Guide

If not, can you let us know which parts you think need clarification?

The client wants to be able to customise the OTP codes instead of cnmaestro generating its own OTPs. For example, cnmaestro generates 6 character codes yet the customer wants it to be 4 character.

Secondly, we want users to redirect to a particular url, but this is archivable only on computer but smartphones and tablets bypass it