Receiving unwanted calls can be a nuisance. The iPhone doesn't have a native feature that allows you to block incoming calls but jailbreaking your phone gives you access to an application that can. iBlacklist enables you to block calls and SMS messages from individual numbers as well as callers using blocked or unknown numbers. The app costs £8.40 and isn't available through the Apple app store, but you can download it using Cydia, an alternative app store for jailbroken iPhones.
Tap the Cydia application on your iPhone to open it. Type iBlacklist into the search box and select the app from the list of results by tapping on it.
Follow the onscreen instructions to pay for and download the app. Once the download has finished, tap "Close Window" to close the Cydia application and return to your iPhone's home screen.
Scroll through your iPhone apps to find the iBlacklist app and tap to open it.
Tap "Blacklists" in the main view to view the current lists of blacklisted numbers or groups. Select "Add new Blacklist."
Choose whether you want to add a number from your contact list, your recent call list or your recent message list, or whether you want to manually add a number and select the appropriate option from the list. If you have chosen to add an existing contact, you will be prompted to select the contact from a list; otherwise you will be asked to enter the number and choose a name for the contact.
Find the row with the red call icon on the configuration page, which will appear after you have selected the contact to block or added the number manually. Set the switch to "On" by swiping your finger across the switch to block calls from this contact. You can also block SMS messages from this contact by setting the switch to "On" next to the red message symbol.
Tap the row marked "Action to be performed" and choose whether you want the call to go straight to voice mail, to be automatically hung up on, to receive a busy signal or to be blocked without your phone ringing, by tapping on the appropriate row. Click the blue button to add the contact to your blacklist. Your changes will be saved and any calls and/or messages from that number will be blocked.
To install iBlacklist you will need to be connected to either a 3G network or a wireless network.
Jailbroken applications are nor supported by Apple. If there is a bug in one of these applications, Apple will not offer support.