The shortlist
6 things that do it.
Built-in iPhone settings (Screen Unknown Callers, set to Silence) that silence calls from numbers not in your contacts and send them to voicemail, plus call screening that asks callers to say why they are calling.
- Free
- Built into the Phone settings; no separate price.
- Paid
- price not checked
- Best at
- Needing no extra app: Apple says Silence Unknown Callers automatically silences calls from numbers not in your contacts and sends them to voicemail.
- The catch
- Apple advises adding expected callers such as family, friends, your child's school or your doctor's office to Contacts so their calls ring, and says calls are not screened while you are roaming.
- ios
Caller ID and spam protection in Google's Phone app, with warnings about potential spam callers and, on Pixel phones, Call Screen.
- Free
- Built into the Phone app on supported Android devices (Android 6.0 and up for basic caller ID and spam protection).
- Paid
- price not checked
- Best at
- Warning you about likely spam callers: Google says it gives information about callers outside your contacts or warnings about potential spam callers.
- The catch
- Google says not all spam calls and robocalls can be detected, and its numbers of unknown callers are sent to Google for identification. Call Screen needs a Pixel phone and does not work while roaming.
- android
Caller ID and spam-blocking app that says it identifies and blocks spam calls and helps search unknown numbers.
- Free
- Free to download, but the UK App Store listing says caller ID and spam blocking on iPhone need a paid subscription.
- Paid
- from £2.99 per month
- Best at
- Identifying unknown numbers: the App Store listing describes spam detection plus a search for unknown numbers.
- The catch
- Its UK App Store privacy label lists data linked to you, including purchases, location, contact information, search history and identifiers, and the listing carries user reviews saying some blocked numbers still get through.
- ios
Spam-blocking and caller ID app.
- Free
- Free to download with in-app purchases (UK App Store); which features are free is not stated.
- Paid
- from £2.99 per month (Lookup Plan)
- Best at
- Caller ID and spam warnings, per its UK App Store listing.
- The catch
- The UK App Store listing says its AI voice detection and intelligent call screening are only available in the United States and Canada, and that features vary by device, OS, carrier and plan.
- ios
A network-level feature of Vodafone's Secure Net Mobile that flags scam, spam and nuisance calls on screen before you answer.
- Free
- Free for the first three months for Vodafone customers, then paid.
- Paid
- from £2 per month
- Best at
- Working with nothing to download: Vodafone says it works automatically in the background for Secure Net Mobile customers.
- The catch
- Only for Vodafone mobile customers, and it is part of Secure Net Mobile, which costs £2 a month after the first three months free.
- network
An O2 network feature that checks phone numbers and tells you when a call might be a scam or spam, alongside Brand ID for genuine business callers.
- Free
- Free to eligible O2 customers (Pay Monthly custom plans, SIM Only plans, O2 Business accounts).
- Paid
- price not checked
- Best at
- Showing a warning for possible scam or spam calls at no extra cost to eligible O2 customers.
- The catch
- Only for O2 Pay Monthly custom plans, SIM Only plans or O2 Business accounts, and iPhone users need iOS 18 or later.
- network
The same shortlist, as a table
| Thing | Free tier | Paid from | Platforms | The catch |
|---|---|---|---|---|
| iPhone Silence Unknown Callers and Call Screeningrel="nofollow noopener" | Built into the Phone settings; no separate price. | not checked | ios | Apple advises adding expected callers such as family, friends, your child's school or your doctor's office to Contacts so their calls ring, and says calls are not screened while you are roaming. |
| Google Phone app: caller ID and spam protectionrel="nofollow noopener" | Built into the Phone app on supported Android devices (Android 6.0 and up for basic caller ID and spam protection). | not checked | android | Google says not all spam calls and robocalls can be detected, and its numbers of unknown callers are sent to Google for identification. Call Screen needs a Pixel phone and does not work while roaming. |
| Truecallerrel="nofollow noopener" | Free to download, but the UK App Store listing says caller ID and spam blocking on iPhone need a paid subscription. | £2.99 per month | ios | Its UK App Store privacy label lists data linked to you, including purchases, location, contact information, search history and identifiers, and the listing carries user reviews saying some blocked numbers still get through. |
| Hiyarel="nofollow noopener" | Free to download with in-app purchases (UK App Store); which features are free is not stated. | £2.99 per month (Lookup Plan) | ios | The UK App Store listing says its AI voice detection and intelligent call screening are only available in the United States and Canada, and that features vary by device, OS, carrier and plan. |
| Vodafone Scam Call Protectionrel="nofollow noopener" | Free for the first three months for Vodafone customers, then paid. | £2 per month | network | Only for Vodafone mobile customers, and it is part of Secure Net Mobile, which costs £2 a month after the first three months free. |
| O2 Call Defencerel="nofollow noopener" | Free to eligible O2 customers (Pay Monthly custom plans, SIM Only plans, O2 Business accounts). | not checked | network | Only for O2 Pay Monthly custom plans, SIM Only plans or O2 Business accounts, and iPhone users need iOS 18 or later. |
How we checked
What we read, and what we haven't tested yet.
On 2026-10-02 we read Apple's Manage unknown callers page, Google's Phone app help pages for caller ID and spam protection and for Call Screen, the UK App Store listings for Truecaller and Hiya, Vodafone's Scam Call Protection press release, O2's nuisance calls help page, BT's Call Protect help page, EE's nuisance calls guide and Citizens Advice's guide. Truecaller's own site refused our fetch. Nothing was tested hands-on.
If none of these fit
The manual way.
Landlines are a different case. BT Call Protect is a free service for BT home phone customers that sends known nuisance callers, and any numbers you add (up to 100), to a junk voicemail. Citizens Advice says registering with the Telephone Preference Service is free, but it won't stop scammers or automated marketing calls. Forward scam texts to 7726, which is free and reports the sender to your network. O2 also takes reports at nuisance@telefonica.com.