How-to submitted by booststuff member arp734

1. Go to your Main Menu.
2. Select Profiles.
3. Your current profile is selected with a checkmark. Press View. Should be one of your softkeys.
4. Scroll down to Call Filter. Highlight it and press Edit. Again it's one of your softkeys.
5. Scroll down and highlight Call Filter. Press OK.
6. Now here you'll have 4 lines.
Phone: Off
Walkie-Talkie: Off
Alerts: Off
Notifications: Off
7. Highlight "Phone: Off" and press OK.
8. BECAREFUL HERE! You'll see 4 options.
Off
All
All Contacts
Some Cntcs
If you select All then ALL your calls will be blocked. All Contacts will block only the people you have in your contacts list. You want to highlight and select Some Cntcs, press OK.
9. Now it lists all your contacts. If the contact isn't on your contact list then press END and keep exiting until you are at your home screen. Add the contact and repeat the steps. Press OK to select each contacts one at a time.
10. Press Done from one of your softkeys. And the contact will be added to your Call Filter List.
11. Keep pressing Done until your profile is saying your profile has been changed.
12. Turn your phone off wait a few seconds and turn it back on.

Congrats! You've added a number to your call filter list.

After asking Boost Mobile Customer Care what exactly Call Filter does, they confirmed it IS to BLOCK unwanted contacts from getting ahold of you.

FYI putting a number on your Call Filter list may not block them 100% of the time. For instance if the unwanted contact calls you, even though they are on your Call Filter list your phone may ring once, or beep. Just remember the filter DOES work.

But this is how you do it for the i425. Your settings on your phone may not have a Call Filter. You're welcome!