Sending PIN codes in SMS is no doubt a much better idea, than not sending it. OTPs provide for greater security, no doubt. However, there are known and described cases of how SMS OTPs sent over a cellular network can be compromised. There are systems emerging to alleviate different aspects of SMS tampering, with various pros and cons. An example is new Chrome APIs to read and transfer SMS content between devices, for users logged in on both devices into their Google account.
Logintap offers another kind of solution, which fits any process without such pre-requisites.
The following main factors of Logintap's SMS OTP security improvement are: