Unknown numbers ringing at dinnertime, sales calls pushing broadband or energy deals, and scam attempts using numbers that look local: nuisance calls remain a daily annoyance for millions of people across the UK. The good news is that a few settings on your phone, plus a handful of free official tools, can cut them down sharply.

Here is how to filter calls straight away on iPhone and Android, and which services to sign up for to curb marketing calls and spoofed numbers.

Filtering calls on iPhone

The most effective filter on iPhone is called "Silence Unknown Callers": it sends every call from a number that is not in your contacts straight to voicemail, so your phone never rings. The number still appears in your Recents list, so you can call back if you need to.

The exact path depends on your iOS version: on the latest releases the feature has been expanded and offers three choices, "Never", "Ask Reason for Calling" and "Silence".

  1. Open Settings and tap "Phone" (on the latest iOS: tap "Apps", then "Phone").
  2. Find "Silence Unknown Callers" or, on newer iOS, "Screen Unknown Callers".
  3. Turn on "Silence" to route every unsaved number to voicemail.

Filtering calls on Android

On Android phones using the Google Phone app, the spam filter takes just a few taps and automatically diverts numbers already flagged as nuisance.

  1. Open the Phone app and tap the three-dot menu in the top right.
  2. Go to "Settings", then "Caller ID & spam".
  3. Switch on "See caller & spam ID" and "Filter spam calls": suspected spam is quietly diverted without ringing your phone.

On a Samsung Galaxy the route is slightly different: open Phone, tap the three dots, then "Settings" and "Block numbers", where you can turn on "Caller ID and spam protection" and also block calls from hidden or withheld numbers.

The trade-off and the middle-ground setting

The "Silence" filter is blunt: it cuts everything that is not in your contacts. The price you pay is the genuine call you might miss, from the hospital calling back to the courier who cannot find your door. Those calls land silently in voicemail, so it is worth checking it now and then.

That is why iOS offers a halfway house, "Ask Reason for Calling": your iPhone answers for you and asks who is calling before it rings. Here is how to pitch it.

  • Turn on "Silence" if you get far more spam than useful calls from numbers you do not know.
  • Pick "Ask Reason for Calling" if you often expect couriers, doctors or tradespeople who are not in your contacts.
  • Register with the Telephone Preference Service to stop live marketing calls at the source.
  • Do not rely on blocking numbers one by one: the caller changes its number with every campaign, so chasing them never ends.
  • Do not trust the number shown on your screen: it can be spoofed to look like a local landline.
  • Never share personal or banking details with an unexpected caller, even if they know your name.

The free official tools in the UK

Beyond your handset settings, a few free UK tools tackle the problem upstream. The first is the Telephone Preference Service (TPS), the free official register that opts you out of live sales calls: once you are on it, legitimate marketing firms are no longer allowed to call you.

You can register free online at tpsonline.org.uk or by calling 0345 070 0707, and it can take up to 28 days to take full effect while organisations update their lists. Mind the limits, though: the TPS does not stop automated recorded calls, scam calls or nuisance texts, because the rules cover only live marketing calls from legitimate companies.

For dodgy text messages, the simplest move is to forward the message to 7726, which spells "SPAM" on the keypad. Forwarding is free and reports the sender to your mobile network, which helps block the number for everyone.

Good to know: suspicious calls can also be reported to your network and to Ofcom. Treating any unexpected request for your details or a payment as a red flag is still the most reliable defence.

The anti-nuisance tools and what each one blocks
Tool What it blocks How to use it
iPhone and Android filters Unsaved numbers and calls already flagged as spam In your phone settings, free
Telephone Preference Service Live sales calls from legitimate UK firms Register free at tpsonline.org.uk (up to 28 days)
Forwarding to 7726 Spam texts (reports the sender to your network) Forward the text to 7726, free
Report to Ofcom / your network Scam and nuisance calls (helps get numbers blocked) Report the number to your provider and Ofcom

Apps and choosing what works

Third-party caller-ID apps add another layer by flagging numbers reported by their community in real time. They are a useful top-up, though they need access to your contacts and call log, which is worth weighing up for privacy.

  • The set-up that actually works
  • A built-in filter switched on, on iPhone or Android.
  • Free registration with the Telephone Preference Service.
  • A bit of caution with unexpected calls and numbers you were not expecting.

If patchy signal is pushing your calls to voicemail anyway, it is worth checking your mobile network and learning how to check network coverage in your area. You can also compare mobile deals to find a plan that suits you.