Spam calls can be annoying, especially when you continue to receive calls from the same number despite ignoring them repeatedly.
Luckily, smartphone manufacturers have been aware of these problems for years, and most modern smartphones offer users the ability to block certain numbers and caller IDs without the need for additional software.
This is true for both Android and iOS devices, and users can also decide to remove numbers from their blocked list later if they change their mind about a certain caller.
There are also numerous ways to screen incoming phone calls to give you an idea of who is calling you.
We have outlined the easiest ways to block certain numbers and screen incoming phone calls below.
Most Android smartphones include a native feature to add numbers to a "blocked" list, preventing certain numbers from contacting you.
This can vary between manufacturers, but the option is usually accessible through the Phone app, under Call Settings.
Users can usually also add numbers to their blocked list by tapping and holding on a number in their call history to bring up a context menu and block the caller.
Some Android smartphones – such as Samsung's Galaxy flagship smartphones – include a built-in smart calling option which screens numbers against a public database and presents you with information on an incoming call.
For other Android users, there are a number of third-party applications available on the Google Play Store which accomplish the same thing.
A popular version of these caller ID apps among South Africans is Truecaller, which offers you the ability to automatically filter spam and telemarketing SMSs.
As there is only one manufacturer of iOS devices – Apple – it is much easier to describe the number blocking process.
To block numbers on your iPhone running iOS 7 or later, you will need to open the Phone app and navigate to Recents. From here, you can tap the "i" symbol next to the unwanted number and tap the "Block this Caller" option that appears in the menu.
Once a number has been blocked on your iPhone, you will no longer receive any calls, texts, or FaceTime calls from the blocked number.
If you want to take your anti-spam measures one step further, however, you can also download a third-party app to automatically screen your communication for telemarketers and scammers.
Once again, Truecaller is a favourite option among iPhone users, and it is available for free from the App Store.
Truecaller for iOS offers the same features as it does on Android, including the ability to automatically identify and block spam and telemarketers.
Other popular caller ID apps for Android and iOS include Whoscall, Showcaller, and CallerSmart.