Usually when you make a phone call, your caller ID (your phone number or sometimes your name) will display on the phone of the person you are calling.
iPhone’s own implementation of Caller ID could help you prevent your number from appearing when you call
other people’s phones. From the Home screen, tap Settings -> Phone -> Show My Caller ID, and then tap the On/Off switch.
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When you are making a phone call using iPhone, there is a mute phone call button appear on the screen. This is a very cool feature. Tap this button to mute your own microphone, so the other guy can’t hear you. (You can still hear him, though.) Now you have a chance to yell upstairs, to clear the phlegm from your throat, or to do anything else you’d rather the other party not hear. Tap again to unmute.
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