diff --git a/api/constants.py b/api/constants.py
index a98612f..f44410c 100644
--- a/api/constants.py
+++ b/api/constants.py
@@ -142,12 +142,3 @@ FORCE_TURN_RELAY = os.getenv("FORCE_TURN_RELAY", "false").lower() == "true"
 # OSS Email/Password Auth
 OSS_JWT_SECRET = os.getenv("OSS_JWT_SECRET", "change-me-in-production")
 OSS_JWT_EXPIRY_HOURS = int(os.getenv("OSS_JWT_EXPIRY_HOURS", "720"))  # 30 days
-
-# REMOVE-AFTER 2026-05-15: transitional flag. When True, Telnyx webhook
-# signature verification is skipped for configs that have no
-# webhook_public_key set (existing configs predating the field). Set in prod
-# through 2026-05-15 to give users time to add their key; once removed,
-# configs without a key will fail signature verification.
-TELNYX_WEBHOOK_VERIFICATION_OPTIONAL = (
-    os.getenv("TELNYX_WEBHOOK_VERIFICATION_OPTIONAL", "false").lower() == "true"
-)
diff --git a/api/services/telephony/providers/telnyx/provider.py b/api/services/telephony/providers/telnyx/provider.py
index e78914b..f14e0f1 100644
--- a/api/services/telephony/providers/telnyx/provider.py
+++ b/api/services/telephony/providers/telnyx/provider.py
@@ -25,7 +25,6 @@ TELNYX_TIMESTAMP_TOLERANCE_SECONDS = 300
 TELNYX_PUBLIC_KEY_BYTES = 32
 TELNYX_SIGNATURE_BYTES = 64
 
-from api.constants import TELNYX_WEBHOOK_VERIFICATION_OPTIONAL
 from api.enums import WorkflowRunMode
 from api.services.telephony.base import (
     CallInitiationResult,
@@ -211,12 +210,6 @@ class TelnyxProvider(TelephonyProvider):
             return False
 
         if not self.webhook_public_key:
-            # REMOVE-AFTER 2026-05-15: transition window. Allow webhooks
-            # through for configs that haven't added the key yet. Remove this
-            # branch along with TELNYX_WEBHOOK_VERIFICATION_OPTIONAL after
-            # the cutoff.
-            if TELNYX_WEBHOOK_VERIFICATION_OPTIONAL:
-                return True
             logger.error("Missing Telnyx webhook_public_key configuration")
             return False
 
diff --git a/api/tests/telephony/telnyx/test_provider.py b/api/tests/telephony/telnyx/test_provider.py
index 3f0f6f3..6462119 100644
--- a/api/tests/telephony/telnyx/test_provider.py
+++ b/api/tests/telephony/telnyx/test_provider.py
@@ -153,45 +153,16 @@ async def test_verify_inbound_signature_rejects_missing_config_public_key():
     _, headers = _signed_headers(body)
     provider = _provider()
 
-    # REMOVE-AFTER 2026-05-15: drop the patch wrapper once
-    # TELNYX_WEBHOOK_VERIFICATION_OPTIONAL is removed; the bare call below
-    # will then assert the only path.
-    with patch(
-        "api.services.telephony.providers.telnyx.provider.TELNYX_WEBHOOK_VERIFICATION_OPTIONAL",
-        False,
-    ):
-        result = await provider.verify_inbound_signature(
-            "https://example.test/api/v1/telephony/inbound/run",
-            json.loads(body),
-            headers,
-            body,
-        )
+    result = await provider.verify_inbound_signature(
+        "https://example.test/api/v1/telephony/inbound/run",
+        json.loads(body),
+        headers,
+        body,
+    )
 
     assert result is False
 
 
-# REMOVE-AFTER 2026-05-15: delete this whole test along with the
-# TELNYX_WEBHOOK_VERIFICATION_OPTIONAL flag.
-@pytest.mark.asyncio
-async def test_verify_inbound_signature_allows_missing_key_when_optional_flag_set():
-    body = _body()
-    _, headers = _signed_headers(body)
-    provider = _provider()
-
-    with patch(
-        "api.services.telephony.providers.telnyx.provider.TELNYX_WEBHOOK_VERIFICATION_OPTIONAL",
-        True,
-    ):
-        result = await provider.verify_inbound_signature(
-            "https://example.test/api/v1/telephony/inbound/run",
-            json.loads(body),
-            headers,
-            body,
-        )
-
-    assert result is True
-
-
 @pytest.mark.asyncio
 async def test_verify_inbound_signature_reads_headers_case_insensitively():
     body = _body()
diff --git a/ui/src/app/telephony-configurations/page.tsx b/ui/src/app/telephony-configurations/page.tsx
index 4d6b4bb..3d6efeb 100644
--- a/ui/src/app/telephony-configurations/page.tsx
+++ b/ui/src/app/telephony-configurations/page.tsx
@@ -181,8 +181,7 @@ export default function TelephonyConfigurationsPage() {
                     ? "1 Telnyx configuration is"
                     : `${telnyxMissingWebhookPublicKeyCount} Telnyx configurations are`}{" "}
                   missing a webhook public key. Without it, Telnyx call status
-                  updates and inbound calls will be rejected starting{" "}
-                  <span className="font-medium">15 May 2026</span>. Copy your
+                  updates and inbound calls are being rejected. Copy your
                   public key from{" "}
                   <span className="whitespace-nowrap">
                     Mission Control Portal → Keys &amp; Credentials → Public Key
diff --git a/ui/src/components/layout/AppSidebar.tsx b/ui/src/components/layout/AppSidebar.tsx
index a6df4a2..147274d 100644
--- a/ui/src/components/layout/AppSidebar.tsx
+++ b/ui/src/components/layout/AppSidebar.tsx
@@ -70,8 +70,7 @@ type SidebarNavSection = {
   items: SidebarNavItem[];
 };
 
-const TELEPHONY_WARNING_DEADLINE = "15 May 2026";
-const TELEPHONY_WARNING_COPY = `Action required before ${TELEPHONY_WARNING_DEADLINE}`;
+const TELEPHONY_WARNING_COPY = "Action required";
 
 const NAV_SECTIONS: SidebarNavSection[] = [
   {
@@ -206,7 +205,7 @@ export function AppSidebar() {
     };
     const warningIndicator = (
       <AlertTriangle
-        aria-label={`Action required on a telephony configuration before ${TELEPHONY_WARNING_DEADLINE}`}
+        aria-label="Action required on a telephony configuration"
         className={cn(
           "text-amber-500",
           isCollapsed ? "absolute -right-0.5 -top-0.5 h-3 w-3" : "ml-auto h-3.5 w-3.5"