Most of your iPhone calls are probably inbound, but sometimes you may want to prevent outgoing calls. Below are some tips on how to stop outgoing calls on an iPhone.

- Make sure before the call that your phone is unlocked. If it's locked, you won't be able to keep incoming calls away from your phone and will have to try again later when your phone is unlocked. This means that you need a passcode for the lock screen so no one else can easily pick up and make a call on your iPhone if it's left unattended. The passcode should be long and complex.
- Put your phone on Airplane Mode. The other party cannot get thru to you if your iPhone is in Airplane Mode, so it prevents calls altogether. On some phones, this is also done by simply setting the ringer and volume too low or off.
- If you still need to take calls, set the ringer back to normal and dial into the call with the phone number of the person that called you. You can do this by dialing *98 before putting their contact info (on Facebook or Twitter).
- Get the free app called 'Do Not Disturb if you have an iPhone.' This will send a signal to the other caller that you're not available, and it lets your cell signal through if you still want to take the call.

- To stop outgoing calls, go to: Settings >'' Phone >'' Call Blocking &'' Identification >'' Block Caller. From this screen, you can enter the telephone number or contact name you wish to block and then save changes by tapping Block Contact.
- To delete a blocked contact, tap Edit at the bottom of the screen and tap the red circle next to the blocked contact you want to be removed. A warning message will pop up asking if you're sure to remove this number — tap Remove Contact. You can now add another contact or continue blocking contacts as desired after tapping Save Changes to edit your list of blocked contacts.
- If you want to do more with your iPhone, many apps can be installed for this purpose. For instance, the "Block Call" app provides a menu of options that you can use to block unwanted calls from anyone on your contact list. You can block the numbers of incoming calls and outgoing calls if you desire.
- Another popular choice among iPhone users is the free app Call Reminder. This works by creating a list of phone numbers and SMS messages that you want to be blocked automatically by default. You can customize the list by entering a specific number. If someone leaves a voicemail message, it'll be saved in the app and synced to all of your devices. When you want to call, you can just go into your contacts and dial the number. If a call comes in, it'll ring through to you or not, depending on how you set it up.
- Another option worth checking out is Block Call Whitelist, which works pretty similarly as above but lets you create an exception list with contacts that won't count as blocked calls due to being in your address book.
- Use iMail: One of the reasons many people like being able to block incoming calls via the Phone app is that you can use it as an address book. And if you have the iMail app installed, incoming calls will be saved in it automatically. You can then use the app to see who called and decide whether or not to call them back. This is an excellent way to block people you don't want to call back.
- If you want the most freedom, you may want to consider getting a VoIP device designed for blocking unwanted calls from landlines and cell phones alike.
- For instance, the AT&''T 908 Home Phone Device blocks all types of unwanted calls automatically, including those from telemarketers and robots. This device is also compatible with connecting to a VoIP service like Vonage, which has even more features. It doesn't require an added monthly fee, and it also gives you the ability to make calls from your computer.
- Get a VoIP phone. You can use this as your main phone number when someone calls, and it will route the call back to your iPhone or cellphone if you choose. When no one is around, simply remove it from service so people can’t reach out via VoIP and try calling your cellphone directly.
Hope these steps help you!