In full disclosure, I work for Infobip.
However, with so many developers utilizing SMS/Voice API's for handset verification or 2FA services, then having issues scaling when they go beyond the USA, this is definitely something to look at.
Unlike other API's, we are actually a telecommunications company that utilizes our own infrastructure, which directly connects to mobile operators.
This results in lower costs, and better delivery. But don't take my word for it, if you're sending SMS or txt2speech, try it out and see the difference in quality yourself.
