In order to use Simple LTC you must turn on 2 factor authentication within Simple LTC. 

Log in to Simple LTC https://secure.simpleltc.com/Account
Once logged into the system then click on My Settings in the upper right hand corner

Enter your cell phone number
Check the box next to Enable SMS Two-Factor Authentication to secure my account information 
Click on the save button. 

In order to login to simple LTC you will need to use your Username, Password, and the code that will sent to you via text message every time you attempt to login to SIMPLE LTC.