diff --git a/core-java-modules/core-java-regex/src/test/java/com/baeldung/regex/phonenumbers/PhoneNumbersRegexUnitTest.java b/core-java-modules/core-java-regex/src/test/java/com/baeldung/regex/phonenumbers/PhoneNumbersRegexUnitTest.java
index afabf47baa..11bf1618b6 100644
--- a/core-java-modules/core-java-regex/src/test/java/com/baeldung/regex/phonenumbers/PhoneNumbersRegexUnitTest.java
+++ b/core-java-modules/core-java-regex/src/test/java/com/baeldung/regex/phonenumbers/PhoneNumbersRegexUnitTest.java
@@ -15,6 +15,13 @@ public class PhoneNumbersRegexUnitTest {
         Matcher matcher = pattern.matcher("2055550125");
         assertTrue(matcher.matches());
     }
+    
+    @Test
+    public void whenMOreThanTenDigits_thenNotCorrect() {
+        Pattern pattern = Pattern.compile("^\\d{10}$");
+        Matcher matcher = pattern.matcher("20555501251");
+        assertFalse(matcher.matches());
+    }
 
     @Test
     public void whenMatchesTenDigitsNumberWhitespacesDotHyphen_thenCorrect() {
@@ -22,6 +29,27 @@ public class PhoneNumbersRegexUnitTest {
         Matcher matcher = pattern.matcher("202 555 0125");
         assertTrue(matcher.matches());
     }
+    
+    @Test
+    public void whenIncludesBracket_thenNotCorrect() {
+        Pattern pattern = Pattern.compile("^(\\d{3}[- .]?){2}\\d{4}$");
+        Matcher matcher = pattern.matcher("202]555 0125");
+        assertFalse(matcher.matches());
+    }
+    
+    @Test
+    public void whenNotStartsWithBatchesOfThreeDigits_thenNotCorrect() {
+        Pattern pattern = Pattern.compile("^(\\d{3}[- .]?){2}\\d{4}$");
+        Matcher matcher = pattern.matcher("2021 555 0125");
+        assertFalse(matcher.matches());
+    }
+    
+    @Test
+    public void whenLastPartWithNoFourDigits_thenNotCorrect() {
+        Pattern pattern = Pattern.compile("^(\\d{3}[- .]?){2}\\d{4}$");
+        Matcher matcher = pattern.matcher("202 555 012");
+        assertFalse(matcher.matches());
+    }
 
     @Test
     public void whenMatchesTenDigitsNumberParenthesis_thenCorrect() {
@@ -30,6 +58,20 @@ public class PhoneNumbersRegexUnitTest {
         assertTrue(matcher.matches());
     }
 
+    @Test
+    public void whenJustOpeningParenthesis_thenNotCorrect() {
+        Pattern pattern = Pattern.compile("^((\\(\\d{3}\\))|\\d{3})[- .]?\\d{3}[- .]?\\d{4}$");
+        Matcher matcher = pattern.matcher("(202 555-0125");
+        assertFalse(matcher.matches());
+    }
+
+    @Test
+    public void whenJustClosingParenthesis_thenNotCorrect() {
+        Pattern pattern = Pattern.compile("^((\\(\\d{3}\\))|\\d{3})[- .]?\\d{3}[- .]?\\d{4}$");
+        Matcher matcher = pattern.matcher("202) 555-0125");
+        assertFalse(matcher.matches());
+    }
+
     @Test
     public void whenMatchesTenDigitsNumberPrefix_thenCorrect() {
         Pattern pattern = Pattern.compile("^(\\+\\d{1,3}( )?)?((\\(\\d{3}\\))|\\d{3})[- .]?\\d{3}[- .]?\\d{4}$");
@@ -37,6 +79,20 @@ public class PhoneNumbersRegexUnitTest {
         assertTrue(matcher.matches());
     }
 
+    @Test
+    public void whenIncorrectPrefix_thenNotCorrect() {
+        Pattern pattern = Pattern.compile("^(\\+\\d{1,3}( )?)?((\\(\\d{3}\\))|\\d{3})[- .]?\\d{3}[- .]?\\d{4}$");
+        Matcher matcher = pattern.matcher("-111 (202) 555-0125");
+        assertFalse(matcher.matches());
+    }
+
+    @Test
+    public void whenTooLongPrefix_thenNotCorrect() {
+        Pattern pattern = Pattern.compile("^(\\+\\d{1,3}( )?)?((\\(\\d{3}\\))|\\d{3})[- .]?\\d{3}[- .]?\\d{4}$");
+        Matcher matcher = pattern.matcher("+1111 (202) 555-0125");
+        assertFalse(matcher.matches());
+    }
+
     @Test
     public void whenMatchesPhoneNumber_thenCorrect() {
         String patterns 
@@ -53,4 +109,21 @@ public class PhoneNumbersRegexUnitTest {
             assertTrue(matcher.matches());
         }
     }
+
+    @Test
+    public void whenNotMatchesPhoneNumber_thenNotCorrect() {
+        String patterns 
+          = "^(\\+\\d{1,3}( )?)?((\\(\\d{3}\\))|\\d{3})[- .]?\\d{3}[- .]?\\d{4}$"
+          + "|^(\\+\\d{1,3}( )?)?(\\d{3}[ ]?){2}\\d{3}$" 
+          + "|^(\\+\\d{1,3}( )?)?(\\d{3}[ ]?)(\\d{2}[ ]?){2}\\d{2}$";
+
+        String[] invalidPhoneNumbers 
+          = {"20555501251","202]555 0125", "2021 555 012", "(202 555-0125", "202) 555-0125", "-111 (202) 555-0125", "+1111 (202) 555-0125", "636 85 789", "636 85 67 893"};
+
+        Pattern pattern = Pattern.compile(patterns);
+        for(String phoneNumber : invalidPhoneNumbers) {
+            Matcher matcher = pattern.matcher(phoneNumber);
+            assertFalse(matcher.matches());
+        }
+    }
 }