diff --git a/api/db/telephony_configuration_client.py b/api/db/telephony_configuration_client.py
index a545aeb..a8f7234 100644
--- a/api/db/telephony_configuration_client.py
+++ b/api/db/telephony_configuration_client.py
@@ -75,6 +75,34 @@ class TelephonyConfigurationClient(BaseDBClient):
             )
             return list(result.scalars().all())
 
+    async def count_telnyx_configs_missing_webhook_public_key(
+        self, organization_id: int
+    ) -> int:
+        """Count Telnyx configs in this org with no webhook_public_key in credentials.
+
+        Used by the org-warnings endpoint to surface a UI nudge until customers
+        paste their portal-issued public key.
+        """
+        async with self.async_session() as session:
+            result = await session.execute(
+                select(func.count(TelephonyConfigurationModel.id)).where(
+                    TelephonyConfigurationModel.organization_id == organization_id,
+                    TelephonyConfigurationModel.provider == "telnyx",
+                    (
+                        TelephonyConfigurationModel.credentials.op("->>")(
+                            "webhook_public_key"
+                        ).is_(None)
+                    )
+                    | (
+                        TelephonyConfigurationModel.credentials.op("->>")(
+                            "webhook_public_key"
+                        )
+                        == ""
+                    ),
+                )
+            )
+            return int(result.scalar() or 0)
+
     async def list_all_telephony_configurations_by_provider(
         self, provider: str
     ) -> List[TelephonyConfigurationModel]:
diff --git a/api/routes/organization.py b/api/routes/organization.py
index 55ba114..f60a413 100644
--- a/api/routes/organization.py
+++ b/api/routes/organization.py
@@ -87,6 +87,17 @@ class TelephonyProvidersMetadataResponse(BaseModel):
     providers: List[TelephonyProviderMetadata]
 
 
+class TelephonyConfigWarningsResponse(BaseModel):
+    """Aggregated telephony-configuration warning counts for the user's org.
+
+    Drives the page banner and nav badge that nudge customers to finish
+    optional-but-recommended configuration steps. Shape is a flat dict so
+    new warning types can be added without breaking the client.
+    """
+
+    telnyx_missing_webhook_public_key_count: int
+
+
 @router.get(
     "/telephony-providers/metadata",
     response_model=TelephonyProvidersMetadataResponse,
@@ -127,6 +138,27 @@ async def get_telephony_providers_metadata(user: UserModel = Depends(get_user)):
     return TelephonyProvidersMetadataResponse(providers=providers)
 
 
+@router.get(
+    "/telephony-config-warnings",
+    response_model=TelephonyConfigWarningsResponse,
+)
+async def get_telephony_config_warnings(user: UserModel = Depends(get_user)):
+    """Return aggregated warning counts for the current org's telephony configs.
+
+    Today this surfaces only Telnyx configs missing ``webhook_public_key``;
+    additional warning types should be added as new fields on the response.
+    """
+    if not user.selected_organization_id:
+        raise HTTPException(status_code=400, detail="No organization selected")
+
+    telnyx_missing = await db_client.count_telnyx_configs_missing_webhook_public_key(
+        user.selected_organization_id
+    )
+    return TelephonyConfigWarningsResponse(
+        telnyx_missing_webhook_public_key_count=telnyx_missing,
+    )
+
+
 def preserve_masked_fields(provider: str, request_dict: dict, existing: dict):
     """If the client re-submitted a masked sensitive field, restore the original."""
     for field_name in _sensitive_fields(provider):
diff --git a/api/services/telephony/providers/telnyx/__init__.py b/api/services/telephony/providers/telnyx/__init__.py
index 558f787..ecbf33f 100644
--- a/api/services/telephony/providers/telnyx/__init__.py
+++ b/api/services/telephony/providers/telnyx/__init__.py
@@ -27,6 +27,7 @@ def _config_loader(value: Dict[str, Any]) -> Dict[str, Any]:
         "provider": "telnyx",
         "api_key": value.get("api_key"),
         "connection_id": value.get("connection_id"),
+        "webhook_public_key": value.get("webhook_public_key"),
         "from_numbers": value.get("from_numbers", []),
     }
 
@@ -124,6 +125,18 @@ _UI_METADATA = ProviderUIMetadata(
                 "blank and we will auto-create one for you on save."
             ),
         ),
+        ProviderUIField(
+            name="webhook_public_key",
+            label="Webhook Public Key",
+            type="textarea",
+            required=False,
+            sensitive=False,
+            description=(
+                "Public key from Mission Control Portal → Keys & Credentials "
+                "→ Public Key. Used to verify Telnyx webhook signatures. "
+                "Without it, webhooks from Telnyx will be rejected."
+            ),
+        ),
         ProviderUIField(
             name="from_numbers",
             label="Phone Numbers",
diff --git a/api/services/telephony/providers/telnyx/config.py b/api/services/telephony/providers/telnyx/config.py
index c51e733..bce04b5 100644
--- a/api/services/telephony/providers/telnyx/config.py
+++ b/api/services/telephony/providers/telnyx/config.py
@@ -18,6 +18,14 @@ class TelnyxConfigurationRequest(BaseModel):
             "stored on the configuration."
         ),
     )
+    webhook_public_key: Optional[str] = Field(
+        default=None,
+        description=(
+            "Webhook public key from Mission Control Portal → Keys & "
+            "Credentials → Public Key. Used to verify Telnyx webhook "
+            "signatures."
+        ),
+    )
     # Phone numbers are managed via the dedicated phone-numbers endpoints; the
     # legacy /telephony-config POST shim still accepts them inline.
     from_numbers: List[str] = Field(
@@ -31,4 +39,5 @@ class TelnyxConfigurationResponse(BaseModel):
     provider: Literal["telnyx"] = Field(default="telnyx")
     api_key: str  # Masked
     connection_id: Optional[str] = None
+    webhook_public_key: Optional[str] = None
     from_numbers: List[str]
diff --git a/api/services/telephony/providers/telnyx/provider.py b/api/services/telephony/providers/telnyx/provider.py
index d127dfa..7ad684b 100644
--- a/api/services/telephony/providers/telnyx/provider.py
+++ b/api/services/telephony/providers/telnyx/provider.py
@@ -48,6 +48,7 @@ class TelnyxProvider(TelephonyProvider):
     def __init__(self, config: Dict[str, Any]):
         self.api_key = config.get("api_key")
         self.connection_id = config.get("connection_id")
+        self.webhook_public_key = config.get("webhook_public_key")
         self.from_numbers = config.get("from_numbers", [])
 
         if isinstance(self.from_numbers, str):
diff --git a/ui/src/app/layout.tsx b/ui/src/app/layout.tsx
index 060fdd3..78a5011 100644
--- a/ui/src/app/layout.tsx
+++ b/ui/src/app/layout.tsx
@@ -11,6 +11,7 @@ import SpinLoader from "@/components/SpinLoader";
 import { Toaster } from "@/components/ui/sonner";
 import { AppConfigProvider } from "@/context/AppConfigContext";
 import { OnboardingProvider } from "@/context/OnboardingContext";
+import { TelephonyConfigWarningsProvider } from "@/context/TelephonyConfigWarningsContext";
 import { UserConfigProvider } from "@/context/UserConfigContext";
 import { AuthProvider } from "@/lib/auth";
 
@@ -63,14 +64,16 @@ export default function RootLayout({
           <AppConfigProvider>
             <Suspense fallback={<SpinLoader />}>
               <UserConfigProvider>
-                <OnboardingProvider>
-                  <PostHogIdentify />
-                  <AppLayout>
-                    {children}
-                  </AppLayout>
-                  <Toaster />
-                  <ChatwootWidget />
-                </OnboardingProvider>
+                <TelephonyConfigWarningsProvider>
+                  <OnboardingProvider>
+                    <PostHogIdentify />
+                    <AppLayout>
+                      {children}
+                    </AppLayout>
+                    <Toaster />
+                    <ChatwootWidget />
+                  </OnboardingProvider>
+                </TelephonyConfigWarningsProvider>
               </UserConfigProvider>
             </Suspense>
           </AppConfigProvider>
diff --git a/ui/src/app/telephony-configurations/page.tsx b/ui/src/app/telephony-configurations/page.tsx
index 0534c8e..4d6b4bb 100644
--- a/ui/src/app/telephony-configurations/page.tsx
+++ b/ui/src/app/telephony-configurations/page.tsx
@@ -1,6 +1,7 @@
 "use client";
 
 import {
+  AlertTriangle,
   ChevronRight,
   Copy,
   ExternalLink,
@@ -44,10 +45,15 @@ import {
   CardTitle,
 } from "@/components/ui/card";
 import { Skeleton } from "@/components/ui/skeleton";
+import { useTelephonyConfigWarnings } from "@/context/TelephonyConfigWarningsContext";
 import { useAuth } from "@/lib/auth";
 
 export default function TelephonyConfigurationsPage() {
   const { user, getAccessToken, loading: authLoading } = useAuth();
+  const {
+    telnyxMissingWebhookPublicKeyCount,
+    refresh: refreshWarnings,
+  } = useTelephonyConfigWarnings();
   const [items, setItems] = useState<TelephonyConfigurationListItem[]>([]);
   const [loading, setLoading] = useState(true);
   const [createOpen, setCreateOpen] = useState(false);
@@ -75,6 +81,14 @@ export default function TelephonyConfigurationsPage() {
     }
   }, [authLoading, user, getAccessToken]);
 
+  // After a save (create/update), the backing config may have flipped between
+  // missing/present webhook_public_key — refresh the cached warning state so
+  // the page banner and nav badge update without a manual reload.
+  const onSaved = useCallback(async () => {
+    await fetchItems();
+    await refreshWarnings();
+  }, [fetchItems, refreshWarnings]);
+
   useEffect(() => {
     fetchItems();
   }, [fetchItems]);
@@ -156,6 +170,30 @@ export default function TelephonyConfigurationsPage() {
           </Button>
         </div>
 
+        {telnyxMissingWebhookPublicKeyCount > 0 && (
+          <div className="mb-6 rounded-md border border-amber-300 bg-amber-50 p-4 text-amber-900 dark:border-amber-800 dark:bg-amber-950 dark:text-amber-200">
+            <div className="flex items-start gap-3">
+              <AlertTriangle className="h-5 w-5 shrink-0 mt-0.5" />
+              <div className="space-y-1 text-sm">
+                <p className="font-medium">Webhook public key not configured</p>
+                <p>
+                  {telnyxMissingWebhookPublicKeyCount === 1
+                    ? "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
+                  public key from{" "}
+                  <span className="whitespace-nowrap">
+                    Mission Control Portal → Keys &amp; Credentials → Public Key
+                  </span>{" "}
+                  and paste it into the affected Telnyx configuration below.
+                </p>
+              </div>
+            </div>
+          </div>
+        )}
+
         {loading ? (
           <div className="grid gap-3">
             <Skeleton className="h-24 w-full" />
@@ -263,13 +301,13 @@ export default function TelephonyConfigurationsPage() {
         open={createOpen}
         onOpenChange={setCreateOpen}
         existing={null}
-        onSaved={fetchItems}
+        onSaved={onSaved}
       />
       <ConfigFormDialog
         open={editOpen}
         onOpenChange={setEditOpen}
         existing={editTarget}
-        onSaved={fetchItems}
+        onSaved={onSaved}
       />
 
       <AlertDialog
diff --git a/ui/src/components/layout/AppSidebar.tsx b/ui/src/components/layout/AppSidebar.tsx
index fc0cb8b..dac3139 100644
--- a/ui/src/components/layout/AppSidebar.tsx
+++ b/ui/src/components/layout/AppSidebar.tsx
@@ -2,6 +2,7 @@
 
 import type { Team } from "@stackframe/stack";
 import {
+  AlertTriangle,
   ArrowUpCircle,
   AudioLines,
   Brain,
@@ -55,6 +56,7 @@ import {
   TooltipTrigger,
 } from "@/components/ui/tooltip";
 import { useAppConfig } from "@/context/AppConfigContext";
+import { useTelephonyConfigWarnings } from "@/context/TelephonyConfigWarningsContext";
 import { useLatestReleaseVersion } from "@/hooks/useLatestReleaseVersion";
 import type { LocalUser } from "@/lib/auth";
 import { useAuth } from "@/lib/auth";
@@ -73,6 +75,8 @@ export function AppSidebar() {
   const { state, isMobile, setOpenMobile } = useSidebar();
   const { provider, getSelectedTeam, logout, user } = useAuth();
   const { config } = useAppConfig();
+  const { telnyxMissingWebhookPublicKeyCount } = useTelephonyConfigWarnings();
+  const hasTelephonyWarning = telnyxMissingWebhookPublicKeyCount > 0;
 
   // On mobile the sidebar renders as a full-width sheet overlay, so treat it
   // as always "expanded" regardless of the desktop collapsed/expanded state.
@@ -191,6 +195,8 @@ export function AppSidebar() {
   const SidebarLink = ({ item }: { item: typeof overviewSection[0] }) => {
     const isItemActive = isActive(item.url);
     const Icon = item.icon;
+    const showWarningDot =
+      item.url === "/telephony-configurations" && hasTelephonyWarning;
 
     if (effectiveState === "collapsed") {
       return (
@@ -204,14 +210,30 @@ export function AppSidebar() {
                   isItemActive && "bg-accent text-accent-foreground"
                 )}
               >
-                <Link href={item.url} onClick={handleMobileNavClick}>
+                <Link href={item.url} onClick={handleMobileNavClick} className="relative">
                   <Icon className="h-4 w-4" />
-                  <span className="sr-only">{item.title}</span>
+                  {showWarningDot && (
+                    <AlertTriangle
+                      aria-hidden
+                      className="absolute -right-0.5 -top-0.5 h-3 w-3 text-amber-500"
+                    />
+                  )}
+                  <span className="sr-only">
+                    {item.title}
+                    {showWarningDot && " — action required before 15 May 2026"}
+                  </span>
                 </Link>
               </SidebarMenuButton>
             </TooltipTrigger>
             <TooltipContent side="right">
-              <p>{item.title}</p>
+              <p>
+                {item.title}
+                {showWarningDot && (
+                  <span className="block text-amber-600 dark:text-amber-400">
+                    Action required before 15 May 2026
+                  </span>
+                )}
+              </p>
             </TooltipContent>
           </Tooltip>
         </TooltipProvider>
@@ -229,6 +251,21 @@ export function AppSidebar() {
         <Link href={item.url} onClick={handleMobileNavClick}>
           <Icon className="h-4 w-4" />
           <span>{item.title}</span>
+          {showWarningDot && (
+            <TooltipProvider delayDuration={0}>
+              <Tooltip>
+                <TooltipTrigger asChild>
+                  <AlertTriangle
+                    aria-label="Action required on a telephony configuration before 15 May 2026"
+                    className="ml-auto h-3.5 w-3.5 text-amber-500"
+                  />
+                </TooltipTrigger>
+                <TooltipContent side="right">
+                  <p>Action required before 15 May 2026</p>
+                </TooltipContent>
+              </Tooltip>
+            </TooltipProvider>
+          )}
         </Link>
       </SidebarMenuButton>
     );
diff --git a/ui/src/context/TelephonyConfigWarningsContext.tsx b/ui/src/context/TelephonyConfigWarningsContext.tsx
new file mode 100644
index 0000000..cb1d094
--- /dev/null
+++ b/ui/src/context/TelephonyConfigWarningsContext.tsx
@@ -0,0 +1,75 @@
+'use client';
+
+import { createContext, ReactNode, useCallback, useContext, useEffect, useRef, useState } from 'react';
+
+import { client } from '@/client/client.gen';
+import { useAuth } from '@/lib/auth';
+
+interface TelephonyConfigWarningsResponse {
+    telnyx_missing_webhook_public_key_count: number;
+}
+
+interface TelephonyConfigWarningsContextType {
+    telnyxMissingWebhookPublicKeyCount: number;
+    refresh: () => Promise<void>;
+    loading: boolean;
+}
+
+const TelephonyConfigWarningsContext = createContext<TelephonyConfigWarningsContextType>({
+    telnyxMissingWebhookPublicKeyCount: 0,
+    refresh: async () => { },
+    loading: false,
+});
+
+// One-shot fetch on first authenticated load. The state is cheap to compute
+// server-side (one indexed JSONB query) but rendering it in both the page
+// banner and the nav badge means we don't want to refetch on every route
+// change. Page-level callers invalidate via refresh() after a save.
+export function TelephonyConfigWarningsProvider({ children }: { children: ReactNode }) {
+    const auth = useAuth();
+    const [count, setCount] = useState(0);
+    const [loading, setLoading] = useState(false);
+    const hasFetched = useRef(false);
+
+    const doFetch = useCallback(async () => {
+        setLoading(true);
+        try {
+            const res = await client.get<TelephonyConfigWarningsResponse>({
+                url: '/api/v1/organizations/telephony-config-warnings',
+            });
+            const data = res.data as TelephonyConfigWarningsResponse | undefined;
+            setCount(data?.telnyx_missing_webhook_public_key_count ?? 0);
+        } catch {
+            setCount(0);
+        } finally {
+            setLoading(false);
+        }
+    }, []);
+
+    useEffect(() => {
+        if (auth.loading || !auth.isAuthenticated || hasFetched.current) return;
+        hasFetched.current = true;
+        doFetch();
+    }, [auth.loading, auth.isAuthenticated, doFetch]);
+
+    const refresh = useCallback(async () => {
+        if (!auth.isAuthenticated) return;
+        await doFetch();
+    }, [auth.isAuthenticated, doFetch]);
+
+    return (
+        <TelephonyConfigWarningsContext.Provider
+            value={{
+                telnyxMissingWebhookPublicKeyCount: count,
+                refresh,
+                loading,
+            }}
+        >
+            {children}
+        </TelephonyConfigWarningsContext.Provider>
+    );
+}
+
+export function useTelephonyConfigWarnings() {
+    return useContext(TelephonyConfigWarningsContext);
+}