A lot of users are asking whether it is possible to block a phone number on the iPhone, calling or texting. How can you stop unwanted numbers calling your iPhone? Unfortunately, there is no incoming call or text blocking feature available on the iPhone (iPhone 5, iPhone 4 etc), but there are other solutions:
1-Contact your carrier, because a true call blocking can be done at the carrier level. However, your carrier may charge an extra fee for this service. For instance,AT&T offers an optional feature called AT&T Smart Limits for Wireless for $4.99 per month (per line) that lets you block calls and texts from up to 30 specific numbers (that you select). Contact your carrier to see if they offer any similar service free or paid.
2-If you want to block calls from telemarketers, you may want to register your iPhone number with the National Do Not Call Registry.
3-You may want to set up Do Not Disturb option in iOS 6. This feature will not block, but silence incoming calls and other alerts. This feature is very useful if you want to silence your phone when you are busy like during a meeting or sleeping.
4-If your device is jailbroken, there is an app called iBlacklist ($12). This app includes features such as the ability to block calls and text from certain numbers.
5-You may create your own block list. To do that (a) create an “ignore” or “spam” or “unwanted” (or whatever you want to call it) contact for numbers and people to block. Tap Contacts and tap the (+) button to add a new contact. Then name it “ignore” or something similar, add the number you wish to block or ignore, and then assign a silent ring tone and disable every alert including sound, tone and vibration for this contact.