How to block unwanted calls and messages
Practical options for reducing unwanted calls and text messages, from carrier tools to app-level blocking.
By AlertaSpam Security Team. Published August 7, 2026
Blocking one number rarely stops the pattern for good — these tools work best combined, since calls and texts both rely on caller ID and sender IDs that are cheap to change.
Blocking unwanted calls
- Check your carrier's app or settings first — most mobile carriers offer a free or low-cost call-filtering service.
- Enable your phone's built-in spam-call detection, in the phone app's settings, if you haven't already.
- Block a specific number directly from your call log for one-off numbers.
- For a number that keeps changing (a common tactic), look it up on AlertaSpam before blocking to understand whether it's part of a wider pattern.
Blocking unwanted text messages
- Most phones let you block a specific sender directly from the messages app, the same as blocking a call.
- Report spam SMS through your carrier's short code if one is available (many carriers offer a free forward-to-report number).
- Remember that an SMS sender name can be spoofed or reused by someone other than the organization it displays — blocking a sender name doesn't guarantee the same tactic won't reappear under a different one.
What not to do
- Don't install a third-party call- or SMS-blocking app without checking what permissions it requests first — it typically needs to see your call log or messages to work, but should not need broader access than that.
- Don't reply 'STOP' to a message from a number or sender you don't recognize — for a spam sender (as opposed to a legitimate marketing list), this can simply confirm your number is active.
Frequently asked questions
Will blocking a number stop calls from the same operation for good?
Often not by itself — many operations rotate through spoofed numbers. Carrier-level and OS-level spam filtering, which look at calling patterns rather than a single number, tend to hold up better over time than blocking numbers one by one.
Is a paid call-blocking app worth it?
Check what your carrier and phone already include for free first — for many people that's already enough. If you add a third-party app, review its permissions and privacy policy before installing, since it will typically need access to your call log or messages.