fix paths for linking (#685)

* fix paths for linking

* fix more broken links

Author: AdiSai

fern/customization/custom-transcriber.mdx

@@ -439,7 +439,7 @@ You'll learn how to:
 - **Streaming support requirement:**  
   The custom transcriber must support streaming. Vapi sends continuous audio data over the WebSocket, and your server must handle this stream in real time.
 - **Authentication:**  
-  For secure transcriber endpoints, use **Custom Credentials** with `credentialId`. Create [Custom Credentials](../server-url/server-authentication) in the dashboard to manage Bearer Token, OAuth 2.0, or HMAC authentication. For backward compatibility, the legacy `secret` field is still supported and sends the value as an `x-vapi-secret` HTTP header.
+  For secure transcriber endpoints, use **Custom Credentials** with `credentialId`. Create [Custom Credentials](../../server-url/server-authentication) in the dashboard to manage Bearer Token, OAuth 2.0, or HMAC authentication. For backward compatibility, the legacy `secret` field is still supported and sends the value as an `x-vapi-secret` HTTP header.
 - **Buffering:**  
   The solution buffers PCM audio and performs simple validation (e.g. ensuring stereo PCM data length is a multiple of 4). If the audio data is malformed, it is trimmed to a valid length.
 - **Channel detection:**  

fern/customization/custom-tts.mdx

@@ -75,7 +75,7 @@ Create authentication credentials in the dashboard and reference them by ID:
 </CodeBlocks>
 
 <Note>
-Create [Custom Credentials](../server-url/server-authentication) in the Vapi dashboard for better security and credential management.
+Create [Custom Credentials](../../server-url/server-authentication) in the Vapi dashboard for better security and credential management.
 </Note>
 
 ### Legacy Authentication Methods

fern/phone-numbers/inbound-sms.mdx

@@ -69,7 +69,7 @@ Update your number to set `smsEnabled: true` if it was previously disabled.
 - **Twilio only**: Other telephony providers are not supported for inbound SMS at this time.
 - **Webhooks**: With `smsEnabled: true`, Vapi manages the Twilio Messaging webhook for you.
 
-For full endpoint details, see the [OpenAPI reference](/api-reference/openapi).
+For full endpoint details, see the [OpenAPI reference](https://api.vapi.ai/api-json).
 
 ## Next steps
 

fern/tools/default-tools.mdx

@@ -124,7 +124,7 @@ There are three methods for sending DTMF in a phone call:
 
 <Note>
 Vapi's DTMF tool integrates with telephony provider APIs to send DTMF tones using the out-of-band RFC 2833 method. This approach is widely supported and more reliable for transmitting the signals, especially in VoIP environments.
-Note, the tool's effectiveness depends on the IVR system's configuration and their capturing method. See our [IVR navigation guide](https://docs.vapi.ai/tools/ivr-navigation) for best practices.
+Note, the tool's effectiveness depends on the IVR system's configuration and their capturing method. See our [IVR navigation guide](https://docs.vapi.ai/ivr-navigation) for best practices.
 </Note>
 
 #### API Request