diff --git a/lead_management.py b/lead_management.py
index a137e83..c0d4050 100644
--- a/lead_management.py
+++ b/lead_management.py
@@ -6,6 +6,7 @@
 import asyncio
 import json
 import logging
+import re
 from dataclasses import asdict, dataclass
 from datetime import datetime, timedelta
 
@@ -14,6 +15,21 @@
 logger = logging.getLogger(__name__)
 
 
+def normalize_phone(phone: str | None) -> str | None:
+    """Best-effort E.164 normalization for US numbers. Never raises; returns the
+    original string when it can't confidently normalize, so a lead is never lost
+    or mangled. Keeps the CRM consistent and makes click-to-call / SMS / dedup
+    reliable (e.g. "(281) 324-3020" and "281-324-3020" both -> "+12813243020")."""
+    if not phone:
+        return phone
+    digits = re.sub(r"\D", "", phone)
+    if len(digits) == 10:
+        return f"+1{digits}"
+    if len(digits) == 11 and digits.startswith("1"):
+        return f"+{digits}"
+    return phone
+
+
 @dataclass
 class Lead:
     """Lead information captured during conversation"""
@@ -103,6 +119,7 @@ def __init__(self, project_id: str = None):
 
     async def create_lead(self, lead: Lead) -> Lead:
         """Create a new lead"""
+        lead.phone = normalize_phone(lead.phone)
         doc_ref = self.db.collection(self.collection_name).document(lead.lead_id)
 
         def _save():
@@ -113,6 +130,7 @@ def _save():
 
     async def update_lead(self, lead: Lead) -> Lead:
         """Update existing lead"""
+        lead.phone = normalize_phone(lead.phone)
         lead.updated_at = datetime.utcnow().isoformat()
         doc_ref = self.db.collection(self.collection_name).document(lead.lead_id)
 
diff --git a/tests/test_lead_phone_normalize.py b/tests/test_lead_phone_normalize.py
new file mode 100644
index 0000000..e04fe91
--- /dev/null
+++ b/tests/test_lead_phone_normalize.py
@@ -0,0 +1,79 @@
+"""Lead phone numbers are normalized to E.164 on create, so the CRM is
+consistent and click-to-call / SMS / dedup-grouping work. Normalization is
+best-effort and never drops data (unrecognized formats pass through unchanged).
+"""
+
+import asyncio
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent))
+
+from lead_management import Lead, LeadManager, normalize_phone
+
+
+def test_normalize_phone_us_formats():
+    assert normalize_phone("(281) 324-3020") == "+12813243020"
+    assert normalize_phone("281-324-3020") == "+12813243020"
+    assert normalize_phone("2813243020") == "+12813243020"
+    assert normalize_phone("1 (281) 324-3020") == "+12813243020"
+    assert normalize_phone("+12813243020") == "+12813243020"  # idempotent
+
+
+def test_normalize_phone_never_loses_data():
+    assert normalize_phone(None) is None
+    assert normalize_phone("") == ""
+    assert normalize_phone("123") == "123"  # too short -> unchanged
+    assert normalize_phone("+44 20 7946 0958") == "+44 20 7946 0958"  # intl -> unchanged
+
+
+def test_create_lead_normalizes_phone():
+    saved = {}
+
+    class _Doc:
+        def set(self, data, **k):
+            saved.update(data)
+
+    class _Coll:
+        def document(self, _id):
+            return _Doc()
+
+    class _DB:
+        def collection(self, _n):
+            return _Coll()
+
+    lm = LeadManager.__new__(LeadManager)  # bypass firestore.Client()
+    lm.db = _DB()
+    lm.collection_name = "leads"
+    lead = Lead(lead_id="x", user_id="u", session_id="s", phone="(281) 324-3020")
+    asyncio.run(lm.create_lead(lead))
+    assert lead.phone == "+12813243020"
+    # Firestore stores via Lead.to_dict() -> asdict(), i.e. snake_case field
+    # names. (The capitalized "Phone" key only exists in to_csv_row().)
+    assert saved.get("phone") == "+12813243020"
+
+
+def test_update_lead_normalizes_phone():
+    """The 'stored phones are E.164' invariant must survive edits, not just
+    creation -- otherwise an admin CRM edit re-introduces a raw number."""
+    saved = {}
+
+    class _Doc:
+        def set(self, data, **k):
+            saved.update(data)
+
+    class _Coll:
+        def document(self, _id):
+            return _Doc()
+
+    class _DB:
+        def collection(self, _n):
+            return _Coll()
+
+    lm = LeadManager.__new__(LeadManager)  # bypass firestore.Client()
+    lm.db = _DB()
+    lm.collection_name = "leads"
+    lead = Lead(lead_id="x", user_id="u", session_id="s", phone="281-324-3020")
+    asyncio.run(lm.update_lead(lead))
+    assert lead.phone == "+12813243020"
+    assert saved.get("phone") == "+12813243020"