While there isn't a way (that we know of) to find out for sure if you've been blocked, beyond getting hold of the person's phone and checking the blocked list, according to sources, here's how to tell if someone has blocked your number:
Step 1- Call the person you suspect is blocking your cell phone number. Listen for a pre-recorded message or the voicemail prompt. Your number may be blocked if you hear a message such as “The caller is not accepting calls.”
Step 2- Call the person's phone from a different number if you suspect the person has blocked your cell number. Your phone is most likely blocked if a call to the person from another number is not redirected to the same pre-recorded message you heard when you called from your phone.
Step 3- Contact a mutual friend and ask them if they know whether the other person has blocked your number. They may volunteer to ask the other person on your behalf, although it may be forward to make such a request yourself.
Find out if your number been blocked by an iPhone on iOS 7 at PC Advisor.
Learn some quick tips on how to block phone numbers & nuisance callers on your iPhone](http://appleinsider.com/articles/14/05/29/ios-quick-tips-how-to-block-nuisance-callers-on-your-iphone) at Apple Insider.