diff --git a/CHANGELOG.md b/CHANGELOG.md
index b65991ea..0aedea9b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,21 @@
 CHANGELOG
 =========
 
+4.5.0
+------------------
+
+* Added `phoneVerificationMethod`, `phoneWasVerificationSuccessful`, and
+  `phoneVerificationTime` to the `Billing` and `Shipping` request objects.
+  These describe the most recent verification of the phone number for the
+  address. The `PhoneVerificationMethod` enum has the values
+  `DELIVERED_CODE`, `NETWORK`, and `OTHER`. Do not set
+  `phoneWasVerificationSuccessful` if no verification was attempted.
+* Fixed enum serialization and email address hashing in locales that
+  change case conversion, such as Turkish (`tr`) and Azerbaijani (`az`).
+  In those locales, some enum values serialized with a dotless `ı`, for
+  example `account_creatıon`, and the web service rejected them. The library
+  now uses `Locale.ROOT` for these case conversions.
+
 4.4.0 (2026-07-21)
 ------------------
 
diff --git a/CLAUDE.md b/CLAUDE.md
index 043a2893..ea5612dc 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -170,14 +170,14 @@ public enum Status {
 
     @Override
     public String toString() {
-        return name().toLowerCase();
+        return name().toLowerCase(Locale.ROOT);
     }
 }
 ```
 
 **How it works:**
 - Enum constants use `UPPER_SNAKE_CASE` (e.g., `DNS_ERROR`, `ISP_EMAIL`)
-- Override `toString()` to return `name().toLowerCase()` for JSON serialization
+- Override `toString()` to return `name().toLowerCase(Locale.ROOT)` for JSON serialization
 - The `Mapper` class configures Jackson with:
   - `READ_ENUMS_USING_TO_STRING` - Deserializes using `toString()`
   - `READ_UNKNOWN_ENUM_VALUES_AS_NULL` - Unknown values become `null` instead of throwing exceptions
diff --git a/README.md b/README.md
index 9cbbd065..caffc206 100644
--- a/README.md
+++ b/README.md
@@ -202,6 +202,9 @@ Transaction request = new Transaction.Builder(
             .lastName("Smith")
             .phoneCountryCode("1")
             .phoneNumber("321-321-3211")
+            .phoneVerificationMethod(Billing.PhoneVerificationMethod.DELIVERED_CODE)
+            .phoneVerificationTime(ZonedDateTime.parse("2026-10-01T14:30:00Z"))
+            .phoneWasVerificationSuccessful(true)
             .postal("06510")
             .region("CT")
             .build()
@@ -254,6 +257,9 @@ Transaction request = new Transaction.Builder(
             .postal("55455")
             .phoneNumber("313-545-3113")
             .phoneCountryCode("1")
+            .phoneVerificationMethod(Shipping.PhoneVerificationMethod.NETWORK)
+            .phoneVerificationTime(ZonedDateTime.parse("2026-10-02T09:15:00Z"))
+            .phoneWasVerificationSuccessful(false)
             .deliverySpeed(Shipping.DeliverySpeed.EXPEDITED)
             .address("32 Washington Ave.")
             .address2("18")
diff --git a/src/main/java/com/maxmind/minfraud/request/AbstractLocation.java b/src/main/java/com/maxmind/minfraud/request/AbstractLocation.java
index 904676e0..6c0eae95 100644
--- a/src/main/java/com/maxmind/minfraud/request/AbstractLocation.java
+++ b/src/main/java/com/maxmind/minfraud/request/AbstractLocation.java
@@ -2,6 +2,8 @@
 
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.maxmind.minfraud.AbstractModel;
+import java.time.ZonedDateTime;
+import java.util.Locale;
 import java.util.regex.Pattern;
 
 /**
@@ -20,6 +22,9 @@ public abstract sealed class AbstractLocation extends AbstractModel
     private final String postal;
     private final String phoneNumber;
     private final String phoneCountryCode;
+    private final PhoneVerificationMethod phoneVerificationMethod;
+    private final Boolean phoneWasVerificationSuccessful;
+    private final ZonedDateTime phoneVerificationTime;
 
     protected AbstractLocation(AbstractLocation.Builder builder) {
         firstName = builder.firstName;
@@ -33,6 +38,9 @@ protected AbstractLocation(AbstractLocation.Builder builder) {
         postal = builder.postal;
         phoneNumber = builder.phoneNumber;
         phoneCountryCode = builder.phoneCountryCode;
+        phoneVerificationMethod = builder.phoneVerificationMethod;
+        phoneWasVerificationSuccessful = builder.phoneWasVerificationSuccessful;
+        phoneVerificationTime = builder.phoneVerificationTime;
     }
 
     /**
@@ -56,6 +64,9 @@ abstract static class Builder<T extends AbstractLocation.Builder<T>> {
         String postal;
         String phoneNumber;
         String phoneCountryCode;
+        PhoneVerificationMethod phoneVerificationMethod;
+        Boolean phoneWasVerificationSuccessful;
+        ZonedDateTime phoneVerificationTime;
 
         /**
          * @param name The first name associated with the address
@@ -162,6 +173,37 @@ public final T phoneNumber(String number) {
             return (T) this;
         }
 
+        /**
+         * @param method The most recent method used to verify the phone number associated with
+         *               the address
+         * @return The builder object.
+         */
+        public final T phoneVerificationMethod(PhoneVerificationMethod method) {
+            phoneVerificationMethod = method;
+            return (T) this;
+        }
+
+        /**
+         * @param wasSuccessful Whether the most recent verification of the phone number
+         *                      associated with the address succeeded. Do not set this if no
+         *                      verification was attempted.
+         * @return The builder object.
+         */
+        public final T phoneWasVerificationSuccessful(Boolean wasSuccessful) {
+            phoneWasVerificationSuccessful = wasSuccessful;
+            return (T) this;
+        }
+
+        /**
+         * @param time The date and time of the most recent verification of the phone number
+         *             associated with the address
+         * @return The builder object.
+         */
+        public final T phoneVerificationTime(ZonedDateTime time) {
+            phoneVerificationTime = time;
+            return (T) this;
+        }
+
         abstract AbstractLocation build();
     }
 
@@ -257,4 +299,56 @@ public final String phoneNumber() {
     public final String phoneCountryCode() {
         return phoneCountryCode;
     }
+
+    /**
+     * @return The most recent method used to verify the phone number associated with the address
+     */
+    @JsonProperty("phone_verification_method")
+    public final PhoneVerificationMethod phoneVerificationMethod() {
+        return phoneVerificationMethod;
+    }
+
+    /**
+     * @return Whether the most recent verification of the phone number associated with the
+     *     address succeeded
+     */
+    @JsonProperty("phone_was_verification_successful")
+    public final Boolean phoneWasVerificationSuccessful() {
+        return phoneWasVerificationSuccessful;
+    }
+
+    /**
+     * @return The date and time of the most recent verification of the phone number associated
+     *     with the address
+     */
+    @JsonProperty("phone_verification_time")
+    public final ZonedDateTime phoneVerificationTime() {
+        return phoneVerificationTime;
+    }
+
+    /**
+     * Enumerated phone verification methods.
+     */
+    public enum PhoneVerificationMethod {
+        /**
+         * A code delivered to the phone, such as by SMS, voice call, or messaging app
+         */
+        DELIVERED_CODE,
+        /**
+         * Verification through the mobile network operator, such as silent network
+         * authentication
+         */
+        NETWORK,
+        /**
+         * Another verification method
+         */
+        OTHER;
+
+        /**
+         * @return a string representation of the object.
+         */
+        public String toString() {
+            return this.name().toLowerCase(Locale.ROOT);
+        }
+    }
 }
diff --git a/src/main/java/com/maxmind/minfraud/request/Email.java b/src/main/java/com/maxmind/minfraud/request/Email.java
index c6159f42..5840821a 100644
--- a/src/main/java/com/maxmind/minfraud/request/Email.java
+++ b/src/main/java/com/maxmind/minfraud/request/Email.java
@@ -11,6 +11,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 import java.util.regex.Pattern;
 
@@ -416,7 +417,7 @@ public String address() {
     }
 
     private String cleanAddress(String address) {
-        address = address.trim().toLowerCase();
+        address = address.trim().toLowerCase(Locale.ROOT);
 
         int domainIndex = address.lastIndexOf('@');
         if (domainIndex == -1 || domainIndex + 1 == address.length()) {
diff --git a/src/main/java/com/maxmind/minfraud/request/Event.java b/src/main/java/com/maxmind/minfraud/request/Event.java
index 1ece32fd..c838b239 100644
--- a/src/main/java/com/maxmind/minfraud/request/Event.java
+++ b/src/main/java/com/maxmind/minfraud/request/Event.java
@@ -6,6 +6,7 @@
 import java.time.ZoneId;
 import java.time.ZonedDateTime;
 import java.util.Date;
+import java.util.Locale;
 
 /**
  * This class contains general information related to the event being scored.
@@ -207,7 +208,7 @@ public enum Type {
          * @return a string representation of the object.
          */
         public String toString() {
-            return this.name().toLowerCase();
+            return this.name().toLowerCase(Locale.ROOT);
         }
     }
 
@@ -228,7 +229,7 @@ public enum Party {
          * @return a string representation of the object.
          */
         public String toString() {
-            return this.name().toLowerCase();
+            return this.name().toLowerCase(Locale.ROOT);
         }
     }
 }
\ No newline at end of file
diff --git a/src/main/java/com/maxmind/minfraud/request/Payment.java b/src/main/java/com/maxmind/minfraud/request/Payment.java
index dcbd8dda..54631913 100644
--- a/src/main/java/com/maxmind/minfraud/request/Payment.java
+++ b/src/main/java/com/maxmind/minfraud/request/Payment.java
@@ -2,6 +2,7 @@
 
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.maxmind.minfraud.AbstractModel;
+import java.util.Locale;
 
 /**
  * The payment information for the transaction.
@@ -283,7 +284,7 @@ public enum Processor {
          * @return a string representation of the object.
          */
         public String toString() {
-            return this.name().toLowerCase();
+            return this.name().toLowerCase(Locale.ROOT);
         }
     }
 
@@ -336,7 +337,7 @@ public enum Method {
          * @return a string representation of the object.
          */
         public String toString() {
-            return this.name().toLowerCase();
+            return this.name().toLowerCase(Locale.ROOT);
         }
     }
 }
diff --git a/src/main/java/com/maxmind/minfraud/request/Shipping.java b/src/main/java/com/maxmind/minfraud/request/Shipping.java
index 43ab51ad..e979f177 100644
--- a/src/main/java/com/maxmind/minfraud/request/Shipping.java
+++ b/src/main/java/com/maxmind/minfraud/request/Shipping.java
@@ -1,6 +1,7 @@
 package com.maxmind.minfraud.request;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
+import java.util.Locale;
 
 /**
  * The shipping information for the transaction.
@@ -71,7 +72,7 @@ public enum DeliverySpeed {
          * @return a string representation of the object.
          */
         public String toString() {
-            return this.name().toLowerCase();
+            return this.name().toLowerCase(Locale.ROOT);
         }
     }
 }
diff --git a/src/main/java/com/maxmind/minfraud/request/TransactionReport.java b/src/main/java/com/maxmind/minfraud/request/TransactionReport.java
index 83c66f7f..e18f5f58 100644
--- a/src/main/java/com/maxmind/minfraud/request/TransactionReport.java
+++ b/src/main/java/com/maxmind/minfraud/request/TransactionReport.java
@@ -3,6 +3,7 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.maxmind.minfraud.AbstractModel;
 import java.net.InetAddress;
+import java.util.Locale;
 import java.util.UUID;
 
 /**
@@ -231,7 +232,7 @@ public enum Tag {
          * @return a string representation of the object.
          */
         public String toString() {
-            return this.name().toLowerCase();
+            return this.name().toLowerCase(Locale.ROOT);
         }
     }
 
diff --git a/src/main/java/com/maxmind/minfraud/response/EmailDomain.java b/src/main/java/com/maxmind/minfraud/response/EmailDomain.java
index 267c7661..efb869d0 100644
--- a/src/main/java/com/maxmind/minfraud/response/EmailDomain.java
+++ b/src/main/java/com/maxmind/minfraud/response/EmailDomain.java
@@ -3,6 +3,7 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.maxmind.minfraud.JsonSerializable;
 import java.time.LocalDate;
+import java.util.Locale;
 
 /**
  * This class contains minFraud response data related to the email domain.
@@ -63,7 +64,7 @@ public enum Classification {
          */
         @Override
         public String toString() {
-            return name().toLowerCase();
+            return name().toLowerCase(Locale.ROOT);
         }
     }
 
diff --git a/src/main/java/com/maxmind/minfraud/response/EmailDomainVisit.java b/src/main/java/com/maxmind/minfraud/response/EmailDomainVisit.java
index c3e1428b..3f3b7175 100644
--- a/src/main/java/com/maxmind/minfraud/response/EmailDomainVisit.java
+++ b/src/main/java/com/maxmind/minfraud/response/EmailDomainVisit.java
@@ -3,6 +3,7 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.maxmind.minfraud.JsonSerializable;
 import java.time.LocalDate;
+import java.util.Locale;
 
 /**
  * This class contains information about an automated visit to the email domain.
@@ -63,7 +64,7 @@ public enum Status {
          */
         @Override
         public String toString() {
-            return name().toLowerCase();
+            return name().toLowerCase(Locale.ROOT);
         }
     }
 
diff --git a/src/test/java/com/maxmind/minfraud/LocaleTest.java b/src/test/java/com/maxmind/minfraud/LocaleTest.java
new file mode 100644
index 00000000..eba90557
--- /dev/null
+++ b/src/test/java/com/maxmind/minfraud/LocaleTest.java
@@ -0,0 +1,65 @@
+package com.maxmind.minfraud;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import com.maxmind.minfraud.request.AbstractLocation;
+import com.maxmind.minfraud.request.Email;
+import com.maxmind.minfraud.request.Event;
+import com.maxmind.minfraud.request.Payment;
+import com.maxmind.minfraud.request.Shipping;
+import com.maxmind.minfraud.request.TransactionReport;
+import com.maxmind.minfraud.response.EmailDomain;
+import com.maxmind.minfraud.response.EmailDomainVisit;
+import java.util.List;
+import java.util.Locale;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Checks that the default locale does not change serialized values. In the tr-TR locale,
+ * {@code "I".toLowerCase()} is a dotless "ı".
+ */
+public class LocaleTest {
+    private final Locale originalLocale = Locale.getDefault();
+
+    @BeforeEach
+    public void setTurkishLocale() {
+        Locale.setDefault(Locale.forLanguageTag("tr-TR"));
+    }
+
+    @AfterEach
+    public void restoreLocale() {
+        Locale.setDefault(originalLocale);
+    }
+
+    @Test
+    public void testEnumToString() {
+        var values = List.<Enum<?>[]>of(
+            AbstractLocation.PhoneVerificationMethod.values(),
+            Shipping.DeliverySpeed.values(),
+            Payment.Processor.values(),
+            Payment.Method.values(),
+            TransactionReport.Tag.values(),
+            Event.Type.values(),
+            Event.Party.values(),
+            EmailDomain.Classification.values(),
+            EmailDomainVisit.Status.values()
+        );
+        for (var enumValues : values) {
+            for (var value : enumValues) {
+                assertEquals(
+                    value.name().toLowerCase(Locale.ROOT),
+                    value.toString(),
+                    value.getClass().getName() + "." + value.name()
+                );
+            }
+        }
+    }
+
+    @Test
+    public void testEmailAddressLowercasing() {
+        var email = new Email.Builder().address("INFO@TEST.org").hashAddress().build();
+        assertEquals("fad0cdbc3804b804116ea8972221d2a1", email.address());
+    }
+}
diff --git a/src/test/java/com/maxmind/minfraud/request/AbstractLocationTest.java b/src/test/java/com/maxmind/minfraud/request/AbstractLocationTest.java
index b8f71ff4..08db206c 100644
--- a/src/test/java/com/maxmind/minfraud/request/AbstractLocationTest.java
+++ b/src/test/java/com/maxmind/minfraud/request/AbstractLocationTest.java
@@ -1,10 +1,14 @@
 package com.maxmind.minfraud.request;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import com.maxmind.minfraud.request.AbstractLocation.Builder;
+import com.maxmind.minfraud.request.AbstractLocation.PhoneVerificationMethod;
+import java.time.ZonedDateTime;
 import org.junit.jupiter.api.Test;
+import org.skyscreamer.jsonassert.JSONAssert;
 
 public abstract class AbstractLocationTest {
     abstract Builder<?> builder();
@@ -100,4 +104,58 @@ public void testPhoneCountryCode() {
         AbstractLocation loc = this.builder().phoneCountryCode("1").build();
         assertEquals("1", loc.phoneCountryCode());
     }
+
+    @Test
+    public void testPhoneVerificationMethod() {
+        AbstractLocation loc = this.builder()
+            .phoneVerificationMethod(PhoneVerificationMethod.DELIVERED_CODE)
+            .build();
+        assertEquals(PhoneVerificationMethod.DELIVERED_CODE, loc.phoneVerificationMethod());
+
+        loc = this.builder().phoneVerificationMethod(PhoneVerificationMethod.NETWORK).build();
+        assertEquals(PhoneVerificationMethod.NETWORK, loc.phoneVerificationMethod());
+
+        loc = this.builder().phoneVerificationMethod(PhoneVerificationMethod.OTHER).build();
+        assertEquals(PhoneVerificationMethod.OTHER, loc.phoneVerificationMethod());
+    }
+
+    @Test
+    public void testPhoneVerificationMethodToString() {
+        assertEquals("delivered_code", PhoneVerificationMethod.DELIVERED_CODE.toString());
+        assertEquals("network", PhoneVerificationMethod.NETWORK.toString());
+        assertEquals("other", PhoneVerificationMethod.OTHER.toString());
+    }
+
+    @Test
+    public void testPhoneWasVerificationSuccessful() {
+        AbstractLocation loc = this.builder().phoneWasVerificationSuccessful(false).build();
+        assertFalse(loc.phoneWasVerificationSuccessful());
+    }
+
+    @Test
+    public void testPhoneVerificationTime() {
+        var time = ZonedDateTime.now();
+        AbstractLocation loc = this.builder().phoneVerificationTime(time).build();
+        assertEquals(time, loc.phoneVerificationTime());
+    }
+
+    @Test
+    public void testPhoneVerificationSerialization() throws Exception {
+        AbstractLocation loc = this.builder()
+            .phoneVerificationMethod(PhoneVerificationMethod.NETWORK)
+            .phoneWasVerificationSuccessful(false)
+            .phoneVerificationTime(ZonedDateTime.parse("2026-10-01T14:30:00Z"))
+            .build();
+
+        var expectedJSON = "{phone_verification_method:'network',"
+            + "phone_was_verification_successful:false,"
+            + "phone_verification_time:'2026-10-01T14:30:00Z'}";
+        JSONAssert.assertEquals(expectedJSON, loc.toJson(), true);
+    }
+
+    @Test
+    public void testPhoneVerificationOmittedWhenUnset() throws Exception {
+        AbstractLocation loc = this.builder().build();
+        JSONAssert.assertEquals("{}", loc.toJson(), true);
+    }
 }
diff --git a/src/test/java/com/maxmind/minfraud/request/RequestTestHelper.java b/src/test/java/com/maxmind/minfraud/request/RequestTestHelper.java
index 606ca5bd..1c20de68 100644
--- a/src/test/java/com/maxmind/minfraud/request/RequestTestHelper.java
+++ b/src/test/java/com/maxmind/minfraud/request/RequestTestHelper.java
@@ -86,6 +86,9 @@ private static Transaction makeTransaction(Email e) throws Exception {
                     .postal("06510")
                     .phoneNumber("123-456-7890")
                     .phoneCountryCode("1")
+                    .phoneVerificationMethod(Billing.PhoneVerificationMethod.DELIVERED_CODE)
+                    .phoneWasVerificationSuccessful(true)
+                    .phoneVerificationTime(ZonedDateTime.parse("2026-10-01T14:30:00Z"))
                     .build()
             ).shipping(
                 new Shipping.Builder()
@@ -100,6 +103,9 @@ private static Transaction makeTransaction(Email e) throws Exception {
                     .postal("73003")
                     .phoneNumber("123-456-0000")
                     .phoneCountryCode("1")
+                    .phoneVerificationMethod(Shipping.PhoneVerificationMethod.NETWORK)
+                    .phoneWasVerificationSuccessful(false)
+                    .phoneVerificationTime(ZonedDateTime.parse("2026-10-02T09:15:00Z"))
                     .deliverySpeed(Shipping.DeliverySpeed.SAME_DAY)
                     .build()
             ).payment(
diff --git a/src/test/resources/test-data/full-request-email-md5.json b/src/test/resources/test-data/full-request-email-md5.json
index 97150805..361ad816 100644
--- a/src/test/resources/test-data/full-request-email-md5.json
+++ b/src/test/resources/test-data/full-request-email-md5.json
@@ -25,7 +25,10 @@
     "country": "US",
     "postal": "06510",
     "phone_number": "123-456-7890",
-    "phone_country_code": "1"
+    "phone_country_code": "1",
+    "phone_verification_method": "delivered_code",
+    "phone_was_verification_successful": true,
+    "phone_verification_time": "2026-10-01T14:30:00Z"
   },
   "shipping": {
     "first_name": "ShipFirst",
@@ -39,6 +42,9 @@
     "postal": "73003",
     "phone_number": "123-456-0000",
     "phone_country_code": "1",
+    "phone_verification_method": "network",
+    "phone_was_verification_successful": false,
+    "phone_verification_time": "2026-10-02T09:15:00Z",
     "delivery_speed": "same_day"
   },
   "payment": {
diff --git a/src/test/resources/test-data/full-request.json b/src/test/resources/test-data/full-request.json
index 09658526..17fb0b9e 100644
--- a/src/test/resources/test-data/full-request.json
+++ b/src/test/resources/test-data/full-request.json
@@ -25,7 +25,10 @@
     "country": "US",
     "postal": "06510",
     "phone_number": "123-456-7890",
-    "phone_country_code": "1"
+    "phone_country_code": "1",
+    "phone_verification_method": "delivered_code",
+    "phone_was_verification_successful": true,
+    "phone_verification_time": "2026-10-01T14:30:00Z"
   },
   "shipping": {
     "first_name": "ShipFirst",
@@ -39,6 +42,9 @@
     "postal": "73003",
     "phone_number": "123-456-0000",
     "phone_country_code": "1",
+    "phone_verification_method": "network",
+    "phone_was_verification_successful": false,
+    "phone_verification_time": "2026-10-02T09:15:00Z",
     "delivery_speed": "same_day"
   },
   "payment": {