docs: clarify EU capacity and signup availability

fern/advanced/sip/sip.mdx

@@ -17,7 +17,11 @@ Use the API base URL, private key, and SIP host from the same Vapi region. Do no
 | United States | `dashboard.vapi.ai` | `https://api.vapi.ai` | `sip.vapi.ai` |
 | European Union | `dashboard.eu.vapi.ai` | `https://api.eu.vapi.ai` | `sip.eu.vapi.ai` |
 
-For EU organizations, create the SIP phone number against the EU API with an EU dashboard private key:
+<Warning>
+Vapi's EU region is at capacity. Vapi does not accept new EU organizations or offer new add-ons for existing EU organizations. New users should [create an account in the US region](https://dashboard.vapi.ai/register). If you require Vapi-hosted EU data residency, [contact Sales](https://vapi.ai/sales).
+</Warning>
+
+For existing EU organizations, create the SIP phone number against the EU API with an EU dashboard private key:
 
 ```bash
 curl -X POST https://api.eu.vapi.ai/phone-number \

fern/calls/call-concurrency.mdx

@@ -12,7 +12,7 @@ Call concurrency represents how many Vapi calls can be active at the same time.
 **In this guide, you'll learn to:**
 - Understand the default concurrency allocation and when it is usually sufficient
 - Keep outbound and inbound workloads within plan limits
-- Increase reserved capacity directly from the Vapi Dashboard
+- Increase reserved capacity directly from the Vapi Dashboard where add-ons are available
 - Inspect concurrency data through API responses and analytics queries
 
 ## What is concurrency?
@@ -28,7 +28,7 @@ Every Vapi account includes **10 concurrent call slots** by default. When all sl
   </Card>
 </CardGroup>
 
-These limits ensure the underlying compute stays reliable for every customer. Higher concurrency requires reserving additional capacity, which Vapi provides through custom or add-on plans.
+These limits ensure the underlying compute stays reliable for every customer. Higher concurrency requires reserving additional capacity, which Vapi provides through custom or add-on plans where capacity is available.
 
 ## Managing concurrency
 
@@ -41,15 +41,19 @@ Batch long lead lists into smaller chunks (for example, 50–100 numbers) and ru
 If you regularly exceed **50,000 minutes per month**, talk with Vapi about:
 
 - **Custom plans** that include higher baked-in concurrency
-- **Add-on bundles** that let you purchase extra call lines only when you need them
+- **Add-on bundles in the US region** that let you purchase extra call lines only when you need them
 
 <Tip>
 Use billing reports to pair minute usage with concurrency spikes so you can upgrade before calls are blocked.
 </Tip>
 
 ## Increase your concurrency limit
 
-You can raise or reserve more call lines without contacting support:
+<Warning>
+Vapi's EU region is at capacity. Vapi does not accept new EU organizations or offer new add-ons for existing EU organizations. New users should [create an account in the US region](https://dashboard.vapi.ai/register). If you require Vapi-hosted EU data residency, [contact Sales](https://vapi.ai/sales).
+</Warning>
+
+In the US region, you can raise or reserve more call lines without contacting support:
 
 1. Open the [Vapi Dashboard](https://dashboard.vapi.ai/settings/billing).
 2. Navigate to **Settings → Billing**.

fern/security-and-privacy/data-flow.mdx

@@ -380,6 +380,10 @@ Even with maximum custom configuration, certain data passes through Vapi's orche
   </Accordion>
 
   <Accordion title="Data residency compliance">
+    <Warning>
+    Vapi's EU region is at capacity. Vapi does not accept new EU organizations or offer new add-ons for existing EU organizations. New users should [create an account in the US region](https://dashboard.vapi.ai/register). If you require Vapi-hosted EU data residency, [contact Sales](https://vapi.ai/sales).
+    </Warning>
+
     - Use **custom bucket storage** in your required region
     - Use **custom LLM** hosted in-region OR provider with regional endpoints
     - Use **custom Voice** hosted in-region if needed