When you're in the middle of a phone call in iOS 7, and you move your iPhone away from your face, you'll see a bunch of buttons. One of those buttons is a mute button, which, when tapped, keeps the person on the other end of the phone call from hearing anything that you say.
In some cases, the mute button can be tapped by accident while you're in the middle of a phone call and it can be a really annoying issue because you may never know that the person on the other end of the line can't hear you until it's too late. Normally, when you tap on the mute button while in the middle of a phone call, the button will glow white indicating that you have mute enabled, but if your iPhone is against your face, then you can't see the button to know that it's glowing.
A new free jailbreak tweak called Disablemute
by iOS developer Burt will let you disable the mute button outright. With this tweak installed, when you try to tap on the mute button in the middle of a phone call, you'll notice that it won't actually do anything. Instead, the person on the other end of the line will continue to be able to hear what you say. Additionally, the button won't glow white, it'll just continue looking like it was never enabled.
With the mute button disabled, you eliminate the risk of tapping on the mute button by accident and turning the phone call into silence for the other person on the line without knowing it.
Disablemute adds a preferences pane to the Settings application (shown above) where you can easily enable or disable the tweak on demand. With the tweak enabled, the mute button is disabled, while vice-versa, the opposite happens.
If you want to give Disablemute a try, it's available for free in Cydia's BigBoss repository. The tweak does require a device with iOS 7 installed on it.
iOS 7.0-7.0.4, Phone application
iPhone 5 running iOS 7.0.4