SMS is a very poor way and an
insecure one to deliver two factor authentication, with very well known and easily exploitable vulnerabilities. Even the US National Institute of Standards and Technology's (NIST) discourages its use.
See a demo of exploiting SMS's insecurities to empty someone's bitcoin wallet at
https://www.youtube.com/watch?v=mLh1Nmqa6OM
In addition, as most have pointed out here, SMS travels extremely poorly and does not work when you have multiple local SIMs (which is the preferred way to travel as a local) or when your phone is lost or stolen, which usually is when you need to access your accounts the most.
Two factor authentication over e-mail, if implemented by the vendor with TLS authentication, is secure. SMS never is. Email also has the advantage of being universally accessible, even in remote places where mobile phones don't work or your provider lacks roaming agreements (as long as you have internet access).
Resist CX's "offer" to send you SMS; if too many people don't do it, they will have no choice but to look into implementing better, and more secure, methods.