Other line can't hear

Had this happen to me for the first time last night, rebooted the phone and it was fine after. It's definitely a software issue.
 
i'd also favor the assertion that this is a software issue. has happened to me several times in the last several months, usually on an important call. reboot fixes the problem, obviously temporarily. very frustrating.
 
I meant to try this but it didn't occur to me at the time it happened. I know if 3G drops out you can activate Airplane Mode for a few seconds and turn it off back to the mobile network and it fixes the dropout, I wonder if it would also help if you have a calling issue like this to hit Airplane Mode and switch back. While still inconvenient, it would save the hassle of having to reboot it everytime.