When iOS 7 beta 3 was released, it appeared to have affected incoming calls. Some users experienced missed calls altogether, while some could not even answer calls, as some calls would appear as two incoming calls:
With this morning’s release of iOS 7 beta 4, these bugs have been squashed by Apple, as confirmed by iPhoneinCanada.ca readers @cfl_fan and @jfroy1979, as both have noted incoming calls now work and the double call issue has disappeared. It’s probably nice to be able to use the phone again.
Let us know if iOS 7 beta 4 has fixed your missed calls from beta 3 in the comments.