diff --git a/internal-import-file/import-document/src/reportimporter/report_parser.py b/internal-import-file/import-document/src/reportimporter/report_parser.py
index 28481d8af67..9526c683d45 100644
--- a/internal-import-file/import-document/src/reportimporter/report_parser.py
+++ b/internal-import-file/import-document/src/reportimporter/report_parser.py
@@ -1,4 +1,5 @@
 import io
+import ipaddress
 import logging
 import os
 from typing import IO, Dict, Iterable, List, Pattern, Tuple
@@ -74,6 +75,17 @@ def _post_parse_observables(
     ) -> Dict:
         self.helper.log_debug(f"Observable match: {ind_match}")
 
+        if observable.stix_target == "Phone-Number.value":
+            try:
+                ipaddress.ip_address(ind_match)
+            except ValueError:
+                pass
+            else:
+                self.helper.log_debug(
+                    f"Discarding phone number match for IP address '{ind_match}'"
+                )
+                return {}
+
         if self._is_whitelisted(observable.filter_regex, ind_match):
             return {}
 
diff --git a/internal-import-file/import-document/tests/test_report_parser_observables.py b/internal-import-file/import-document/tests/test_report_parser_observables.py
new file mode 100644
index 00000000000..3814a185669
--- /dev/null
+++ b/internal-import-file/import-document/tests/test_report_parser_observables.py
@@ -0,0 +1,63 @@
+from pathlib import Path
+from unittest.mock import MagicMock
+
+import pytest
+from reportimporter.constants import RESULT_FORMAT_CATEGORY
+from reportimporter.core import ReportImporter
+from reportimporter.models import Observable
+from reportimporter.report_parser import ReportParser
+
+
+def _build_parser() -> ReportParser:
+    config_path = (
+        Path(__file__).resolve().parent.parent
+        / "src"
+        / "reportimporter"
+        / "config"
+        / "observable_config.ini"
+    )
+    observables = ReportImporter._parse_config(str(config_path), Observable)
+    return ReportParser(
+        helper=MagicMock(),
+        entity_list=[],
+        observable_list=observables,
+    )
+
+
+@pytest.mark.parametrize(
+    "address",
+    [
+        # RFC 5737 documentation ranges.
+        "192.0.2.123",
+        "198.51.100.42",
+        "203.0.113.42",
+        # Public IPv4 controls.
+        "1.1.1.1",
+        "1.2.3.4",
+    ],
+)
+def test_valid_ipv4_address_is_not_reclassified_as_phone_number(address):
+    result = _build_parser().parse(f"Observed traffic from {address}.")
+
+    assert result[address][RESULT_FORMAT_CATEGORY] == "IPv4-Addr.value"
+
+
+def test_filtered_ipv4_address_is_not_reclassified_as_phone_number():
+    address = "8.8.8.8"
+    result = _build_parser().parse(f"Observed traffic from {address}.")
+
+    assert address not in result
+
+
+@pytest.mark.parametrize(
+    "phone_number",
+    [
+        # ACMA fictional-use number
+        "0491 570 006",
+        "+61 491 570 006",
+    ],
+)
+def test_phone_number_is_still_classified_as_phone_number(phone_number):
+    result = _build_parser().parse(f"Call {phone_number} for assistance.")
+
+    assert result[phone_number][RESULT_FORMAT_CATEGORY] == "Phone-Number.value"