diff --git a/cpp/test/phonenumbers/fuzz_phone.cc b/cpp/test/phonenumbers/fuzz_phone.cc
index d9cc5312fd..a4e326d72a 100644
--- a/cpp/test/phonenumbers/fuzz_phone.cc
+++ b/cpp/test/phonenumbers/fuzz_phone.cc
@@ -28,7 +28,9 @@ limitations under the License.
 #include "phonenumbers/stringutil.h"
 #include "phonenumbers/asyoutypeformatter.h"
 #include "phonenumbers/shortnumberinfo.h"
+#include "phonenumbers/geocoding/phonenumber_offline_geocoder.h"
 #include <fuzzer/FuzzedDataProvider.h>
+#include <unicode/locid.h>
 
 using google::protobuf::RepeatedPtrField;
 
@@ -205,5 +207,21 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   phone_util->FormatByPattern(phone_number, number_format, number_formats, &formatted);
   formatted.clear();
 
+  // Fuzz with OfflineGeocoder
+  i18n::phonenumbers::PhoneNumberOfflineGeocoder geocoder;
+  std::string language = fuzzed_data.ConsumeRandomLengthString(3);
+  std::string country = fuzzed_data.ConsumeRandomLengthString(3);
+  icu::Locale locale(language.c_str(), country.c_str());
+
+  geocoder.GetDescriptionForNumber(phone_number, locale);
+
+  std::string user_region = fuzzed_data.ConsumeBytesAsString(2);
+  geocoder.GetDescriptionForNumber(phone_number, locale, user_region);
+
+  if (phone_util->IsValidNumber(phone_number)) {
+    geocoder.GetDescriptionForValidNumber(phone_number, locale);
+    geocoder.GetDescriptionForValidNumber(phone_number, locale, user_region);
+  }
+
   return 0;
 }
diff --git a/cpp/test/phonenumbers/fuzz_phone_proto.cc b/cpp/test/phonenumbers/fuzz_phone_proto.cc
new file mode 100644
index 0000000000..77fa6fe166
--- /dev/null
+++ b/cpp/test/phonenumbers/fuzz_phone_proto.cc
@@ -0,0 +1,100 @@
+/* Copyright 2026 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+#include <string>
+#include <vector>
+
+#include "phonenumbers/phonenumber.pb.h"
+#include "phonenumbers/phonenumberutil.h"
+#include "phonenumbers/shortnumberinfo.h"
+#include "phonenumbers/geocoding/phonenumber_offline_geocoder.h"
+#include <fuzzer/FuzzedDataProvider.h>
+#include <unicode/locid.h>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  FuzzedDataProvider fuzzed_data(data, size);
+
+  i18n::phonenumbers::PhoneNumber phone_number;
+  
+  // Split data: some for proto parsing, some for other parameters
+  size_t proto_size = fuzzed_data.ConsumeIntegralInRange<size_t>(0, size);
+  std::vector<uint8_t> proto_data = fuzzed_data.ConsumeBytes<uint8_t>(proto_size);
+  
+  if (!phone_number.ParsePartialFromArray(proto_data.data(), proto_data.size())) {
+    return 0;
+  }
+
+  // Avoid OOM from huge number_of_leading_zeros or long strings
+  if (phone_number.number_of_leading_zeros() > 1024) {
+    return 0;
+  }
+  if (phone_number.raw_input().size() > 1024 ||
+      phone_number.extension().size() > 1024 ||
+      phone_number.preferred_domestic_carrier_code().size() > 1024) {
+    return 0;
+  }
+
+  i18n::phonenumbers::PhoneNumberUtil* phone_util = 
+      i18n::phonenumbers::PhoneNumberUtil::GetInstance();
+
+  // Fuzz with the parsed phone_number
+  phone_util->IsPossibleNumber(phone_number);
+  phone_util->IsValidNumber(phone_number);
+  
+  std::string region = fuzzed_data.ConsumeRandomLengthString(3);
+  phone_util->IsValidNumberForRegion(phone_number, region);
+  
+  std::string formatted;
+  phone_util->Format(phone_number, i18n::phonenumbers::PhoneNumberUtil::E164, &formatted);
+  phone_util->Format(phone_number, i18n::phonenumbers::PhoneNumberUtil::INTERNATIONAL, &formatted);
+  phone_util->Format(phone_number, i18n::phonenumbers::PhoneNumberUtil::NATIONAL, &formatted);
+  phone_util->Format(phone_number, i18n::phonenumbers::PhoneNumberUtil::RFC3966, &formatted);
+
+  phone_util->GetLengthOfGeographicalAreaCode(phone_number);
+  phone_util->GetLengthOfNationalDestinationCode(phone_number);
+  
+  phone_util->GetNumberType(phone_number);
+  
+  std::string region_code;
+  phone_util->GetRegionCodeForNumber(phone_number, &region_code);
+
+  phone_util->IsNumberGeographical(phone_number);
+  phone_util->IsNumberGeographical(phone_util->GetNumberType(phone_number), phone_number.country_code());
+  
+  phone_util->IsAlphaNumber(phone_number.raw_input());
+  
+  i18n::phonenumbers::PhoneNumber phone_number_copy(phone_number);
+  phone_util->TruncateTooLongNumber(&phone_number_copy);
+
+  // Fuzz with ShortNumberInfo
+  i18n::phonenumbers::ShortNumberInfo short_info;
+  short_info.IsPossibleShortNumber(phone_number);
+  short_info.IsValidShortNumber(phone_number);
+  short_info.IsPossibleShortNumberForRegion(phone_number, region);
+  short_info.IsValidShortNumberForRegion(phone_number, region);
+  short_info.GetExpectedCost(phone_number);
+
+  // Fuzz with OfflineGeocoder
+  i18n::phonenumbers::PhoneNumberOfflineGeocoder geocoder;
+  std::string language = fuzzed_data.ConsumeRandomLengthString(3);
+  std::string country = fuzzed_data.ConsumeRandomLengthString(3);
+  icu::Locale locale(language.c_str(), country.c_str());
+
+  geocoder.GetDescriptionForNumber(phone_number, locale);
+  geocoder.GetDescriptionForValidNumber(phone_number, locale);
+  geocoder.GetDescriptionForValidNumber(phone_number, locale, country);
+
+  return 0;
+}