If you use an internet-based text messaging app such as WhatsApp, blocking a person's number in contacts won't be enough. They will still message you on other apps, so you'll have to manually block that person on every app. Fortunately, most text messaging apps provide this option. In WhatsApp, blocking a number works this way:

1. Select a person from Contacts or Conversations.

2. Tap on the three vertical dots in the top right corner of the screen.

3. Select “View contact.”

4. Scroll down and select “Block.”

These steps will differ in minor ways on other apps such as Signal or Telegram.

Some Android devices have this feature, and others don’t. Typically, this feature is available in the exact location where you block specific numbers and contacts.

If your Android phone allows you to block specific phrases, that can filter many spam messages. Users can create phrases such as "You have won" or "One time offer," or anything similar to filter out unwanted messages.

Most major carriers have provided this service to their users. If you receive too many spam messages or want to block specific numbers, you can reach out to your carrier and check your options.

Many parents choose to do so when they purchase a smartphone for their children. For example, Verizon allows users to block calls, messages, and even emails and domains.

T-Mobile goes a step further and allows users to block all chargeable text messages. AT&T has a mobile security app that protects users from spammy emails and text messages.