diff --git a/api.ts b/api.ts
index 3822305..cedb527 100644
--- a/api.ts
+++ b/api.ts
@@ -9,22 +9,38 @@
  * ---------------------------------------------------------------
  */
 
-export class CreateWebCallDTO {
+export class CreateCallAssistantDTO {
   /**
    * This is the assistant that will be used for the call. To use a transient assistant, use `assistant` instead.
    */
-  assistantId?: string;
+  assistantId?: string | null;
 
   /**
-   * Overrides for the assistant's settings and template variables.
+   * Overrides for a single assistant's settings and template variables.
    */
-  assistantOverrides?: OverrideAssistantDTO;
+  assistantOverride?: OverrideAssistantDTO;
+
+  /**
+   * Individual overrides for multiple assistant settings and template variables.
+   * If only one override is provided and multiple assistants are used, it will apply to all assistants.
+   * Otherwise, the number of overrides must match the number of assistants.
+   */
+  assistantOverrides?: OverrideAssistantDTO[];
 
   /**
    * This is the assistant that will be used for the call. To use an existing assistant, use `assistantId` instead.
    */
   assistant?: CreateAssistantDTO;
 
+  /**
+   * This is the set of all assistants that can be used for the call.
+   * The call can be transferred between these assistants.
+   * The first assistant in the array will be the primary assistant that starts the call.
+   */
+  assistants?: CreateAssistantDTO[];
+}
+
+export class CreateWebCallDTO extends CreateCallAssistantDTO {
   /**
    * This will expose SIP URI you can use to connect to the call. Disabled by default.
    */
@@ -2303,7 +2319,7 @@ export interface Call {
   metadata?: object;
 }
 
-export interface CreateOutboundCallDTO {
+export interface CreateOutboundCallDTO extends CreateCallAssistantDTO {
   /**
    * This is the maximum number of seconds that the call will last. When the call reaches this duration, it will be ended.
    * @min 10
@@ -2311,12 +2327,6 @@ export interface CreateOutboundCallDTO {
    * @example 1800
    */
   maxDurationSeconds?: number;
-  /** This is the assistant that will be used for the call. To use a transient assistant, use `assistant` instead. */
-  assistantId?: string | null;
-  /** Overrides for the assistant's settings and template variables. */
-  assistantOverrides?: OverrideAssistantDTO;
-  /** This is the assistant that will be used for the call. To use an existing assistant, use `assistantId` instead. */
-  assistant?: CreateAssistantDTO;
   /**
    * This is the customer that will be called. To call a transient customer , use `customer` instead.
    *
diff --git a/vapi.ts b/vapi.ts
index bef031f..3c841f0 100644
--- a/vapi.ts
+++ b/vapi.ts
@@ -97,7 +97,6 @@ export default class Vapi extends VapiEventEmitter {
   private started: boolean = false;
   private call: DailyCall | null = null;
   private speakingTimeout: NodeJS.Timeout | null = null;
-  private averageSpeechLevel: number = 0;
 
   constructor(apiToken: string, apiBaseUrl?: string) {
     super();
@@ -113,13 +112,18 @@ export default class Vapi extends VapiEventEmitter {
   }
 
   async start(
-    assistant: CreateAssistantDTO | string,
-    assistantOverrides?: OverrideAssistantDTO,
+    assistant?: CreateAssistantDTO | string,
+    assistants?: CreateAssistantDTO[],
+    assistantOverride?: OverrideAssistantDTO,
+    assistantOverrides?: OverrideAssistantDTO[],
   ): Promise<Call | null> {
+    if (!assistant && !assistants) {
+      throw new Error('Assistant or assistants must be provided.');
+    }
+
     if (this.started) {
       return null;
     }
-
     this.started = true;
 
     try {
@@ -127,6 +131,8 @@ export default class Vapi extends VapiEventEmitter {
         await client.call.callControllerCreateWebCall({
           assistant: typeof assistant === 'string' ? undefined : assistant,
           assistantId: typeof assistant === 'string' ? assistant : undefined,
+          assistants,
+          assistantOverride,
           assistantOverrides,
         })
       ).data;