For a mobile app, I developed recently, I tried the following services: https://www.nexmo.com/product/verify/ https://www.nexmo.com/product/verify/ https://get

For a mobile app, I developed recently, I tried the following services: https://www.nexmo.com/product/verify/ https://www.nexmo.com/product/verify/ https://getprove.com/ https://getprove.com/ In terms of ease of use and reliability, I preferred Nexmo. But however, I faced issues sending sms to VOIP numbers with Nexmo. I ended up using Twilio and Parse (it was the backend anyway) to get a verification service running. You can use this http://shamadeh.com/blog/web/mobile/twilio/parse/2014/07/31/VerifyPhoneNumbersTwilioAndParse.html http://shamadeh.com/blog/web/mobile/twilio/parse/2014/07/31/... as a starting point!