Have people asked you why you're blocking your phone number? The iPhone can automatically turn off your caller ID when dialing out. Chances are, if your iPhone number is blocked on other people's phones this setting is engaged. To show others your phone number follow these steps:
1. Navigate to Settings -> Phone -> Show My Caller ID
2. Select ON
Now when you call, devices capable of reading the caller ID will display your number instead of a "Blocked" message.