Phone calls from certain numbers can be blocked on a Sony Ericsson phone by navigating to the phone's home screen and clicking on the menu button, selecting the settings option, then clicking on the calls option, then selecting the manage calls option and then the accept calls button. There should be a sub-option available titled "only from list."
This option will enable the user to create a custom list of contacts from their phone book database or by simply manually entering phone numbers. This way, any numbers that haven't been added to this list will blocked. This feature can be disadvantageous because contacts that are not on the list cannot make calls to the user. Because of this, it is important to add any newly acquired contacts to the list.
It is also possible, though, that certain Sony Ericsson phones may not have this feature. If this is the case, the user should contact the service provider. They will likely be able to arrange for certain phone numbers to be blocked for the specific phone. There may be a fee attached to this service, though. This is the case for AT&T, which requires a monthly charge to block certain phone numbers from calling a user's phone.