I've been having similar problems all day since i updated to beta 6 last night. here is the list
incoming calls, phone not ringing, slide to unlock would answer the call but no sound
hanging up a call would not hang up, green call bar active (hard reset again)
wifi signal completely absent from menu bar (hard reset, settings app then completely unresponsive)
would dial a call, phone would hang & then freeze
honestly, i've hard reseted or powered off the phone at least 30 times today. the last four hours, the phone has been good as gold...
i've been on the beta train since ios7, with 4/4S/5S/6, never had the above issues with any beta apart from this one and beta5.
i'm not a developer, just an Apple "nutter" since 1998, fully aware of betas and their "issues", i'm just stating my experience from the last two betas.