Go into the Blocked Messages folder once a month and hit "Delete All." This keeps your voicemail box clean and prevents the "Voicemail Full" error. The Bottom Line Blocking a number on iPhone is great for your sanity, but it isn't a complete firewall. Think of the Blocked Messages folder as a spam folder for your voicemail. It’s there if you need it, but out of the way so you don't have to deal with it.

We’ve all been there. You block a number to stop the spam calls, the robocalls, or that ex you’d rather forget. You assume that’s the end of it—out of sight, out of mind.

But here’s a secret most iPhone users don’t know: