diff --git a/core/packages/gax/src/clientInterface.ts b/core/packages/gax/src/clientInterface.ts
index b9f3bd8b8e9..bf4571d6268 100644
--- a/core/packages/gax/src/clientInterface.ts
+++ b/core/packages/gax/src/clientInterface.ts
@@ -29,9 +29,7 @@ import * as longrunning from './longRunningCalls/longrunning';
 import * as operationProtos from '../protos/operations';
 
 export interface ClientOptions
-  extends GrpcClientOptions,
-    GoogleAuthOptions,
-    ClientStubOptions {
+  extends GrpcClientOptions, GoogleAuthOptions, ClientStubOptions {
   libName?: string;
   libVersion?: string;
   clientConfig?: gax.ClientConfig;
@@ -42,6 +40,10 @@ export interface ClientOptions
   // No preference; exception will be thrown if both are set to different values.
   universeDomain?: string;
   universe_domain?: string;
+  /**
+   * Whether to enable telemetry tracing for the client.
+   */
+  enableTelemetryTracing?: boolean;
 }
 
 export interface Descriptors {
diff --git a/core/packages/gax/src/createApiCall.ts b/core/packages/gax/src/createApiCall.ts
index b3fdee987a6..e161879d5c9 100644
--- a/core/packages/gax/src/createApiCall.ts
+++ b/core/packages/gax/src/createApiCall.ts
@@ -66,8 +66,7 @@ export function createApiCall(
   const funcPromise = typeof func === 'function' ? Promise.resolve(func) : func;
   // the following apiCaller will be used for all calls of this function...
   const apiCaller = createAPICaller(settings, descriptor);
-
-  return (
+  const invokeCall = (
     request: RequestType,
     callOptions?: CallOptions,
     callback?: APICallback,
@@ -154,7 +153,12 @@ export function createApiCall(
       .then((apiCall: SimpleCallbackFunction) => {
         // After adding retries / timeouts, the call function becomes simpler:
         // it only accepts request and callback.
-        currentApiCaller.call(apiCall, request, thisSettings, ongoingCall);
+        return currentApiCaller.call(
+          apiCall,
+          request,
+          thisSettings,
+          ongoingCall,
+        );
       })
       .catch(err => {
         currentApiCaller.fail(ongoingCall, err);
@@ -164,4 +168,5 @@ export function createApiCall(
     // or to cancel the ongoing call.
     return currentApiCaller.result(ongoingCall);
   };
+  return invokeCall;
 }
diff --git a/core/packages/gax/src/gax.ts b/core/packages/gax/src/gax.ts
index a38152c2429..33f8d1672d3 100644
--- a/core/packages/gax/src/gax.ts
+++ b/core/packages/gax/src/gax.ts
@@ -170,6 +170,7 @@ export interface CallOptions {
   longrunning?: BackoffSettings;
   apiName?: string;
   retryRequestOptions?: RetryRequestOptions;
+  enableTelemetryTracing?: boolean;
 }
 
 export class CallSettings {
@@ -186,6 +187,7 @@ export class CallSettings {
   longrunning?: BackoffSettings;
   apiName?: string;
   retryRequestOptions?: RetryRequestOptions;
+  enableTelemetryTracing?: boolean;
 
   /**
    * @param {Object} settings - An object containing parameters of this settings.
@@ -219,6 +221,7 @@ export class CallSettings {
       'longrunning' in settings ? settings.longrunning : undefined;
     this.apiName = settings.apiName ?? undefined;
     this.retryRequestOptions = settings.retryRequestOptions;
+    this.enableTelemetryTracing = settings.enableTelemetryTracing;
   }
 
   /**
@@ -242,6 +245,7 @@ export class CallSettings {
     let longrunning = this.longrunning;
     let apiName = this.apiName;
     let retryRequestOptions = this.retryRequestOptions;
+    let enableTelemetryTracing = this.enableTelemetryTracing;
 
     // If the user provides a timeout to the method, that timeout value will be used
     // to override the backoff settings.
@@ -297,6 +301,9 @@ export class CallSettings {
     if ('retryRequestOptions' in options) {
       retryRequestOptions = options.retryRequestOptions;
     }
+    if ('enableTelemetryTracing' in options) {
+      enableTelemetryTracing = options.enableTelemetryTracing;
+    }
 
     return new CallSettings({
       timeout,
@@ -309,6 +316,7 @@ export class CallSettings {
       isBundling,
       apiName,
       retryRequestOptions,
+      enableTelemetryTracing,
     });
   }
 }
diff --git a/core/packages/gax/src/index.ts b/core/packages/gax/src/index.ts
index d9c82f34530..55c13393378 100644
--- a/core/packages/gax/src/index.ts
+++ b/core/packages/gax/src/index.ts
@@ -113,7 +113,13 @@ export {
   PaginationResponse,
 } from './clientInterface';
 
-export {makeUUID, decodeAnyProtosInArray, decodeProtobufAny} from './util';
+export {
+  makeUUID,
+  decodeAnyProtosInArray,
+  decodeProtobufAny,
+  checkTelemetryEnabled,
+  StaticTraceContext,
+} from './util';
 
 export {ServiceError, ChannelCredentials} from '@grpc/grpc-js';
 export {warn} from './warnings';
diff --git a/core/packages/gax/src/util.ts b/core/packages/gax/src/util.ts
index 16f32f56eb7..0492a4321c2 100644
--- a/core/packages/gax/src/util.ts
+++ b/core/packages/gax/src/util.ts
@@ -14,12 +14,38 @@
  * limitations under the License.
  */
 
+import {CallSettings} from './gax';
+
 const PROTO_TYPE_PREFIX = 'type.googleapis.com/';
 const NUM_OF_PARTS_IN_PROTO_TYPE_NAME = 2;
 
 const randomUUID = () =>
   globalThis.crypto?.randomUUID() || require('crypto').randomUUID();
 
+/**
+ * The static trace context is information about the Google Cloud client library that is
+ * used to generate telemetry tracing information.
+ */
+export interface StaticTraceContext {
+  gcpClientService?: string;
+  gcpVersion?: string;
+  gcpRepo?: string;
+  gcpArtifact?: string;
+}
+
+/**
+ * Checks if telemetry tracing is enabled
+ * @param settings
+ * @returns true if telemetry tracing is enabled, false otherwise
+ */
+export function checkTelemetryEnabled(settings?: CallSettings): boolean {
+  const tracingEnabled =
+    Boolean(settings?.enableTelemetryTracing) &&
+    process.env.GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED === 'true' &&
+    settings?.otherArgs?.internalTelemetryInfo !== undefined;
+  return Boolean(tracingEnabled);
+}
+
 function words(str: string, normalize = false) {
   if (normalize) {
     // strings like somethingABCSomething are special case for protobuf.js,
diff --git a/core/packages/gax/test/unit/apiCallable.ts b/core/packages/gax/test/unit/apiCallable.ts
index f341ec12f01..f7cfaed4148 100644
--- a/core/packages/gax/test/unit/apiCallable.ts
+++ b/core/packages/gax/test/unit/apiCallable.ts
@@ -329,6 +329,31 @@ describe('createApiCall', () => {
       );
     }
   });
+
+  describe('in regards to OpenTelemetry Tracing', () => {
+    afterEach(() => {
+      delete process.env.GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED;
+    });
+
+    it('creates an api call when GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED and CallSettings field is set', () => {
+      process.env.GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED = 'true';
+      const mockCallOptions: gax.CallOptions = {
+        enableTelemetryTracing: true,
+        otherArgs: {
+          internalTelemetryInfo: {
+            gcpClientService: 'test.googleapis.com',
+          },
+        },
+      };
+      const apiCall = createApiCall(() => {}, {settings: mockCallOptions});
+      assert.strictEqual(typeof apiCall, 'function');
+    });
+
+    it('creates an api call when GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED is not set', () => {
+      const apiCall = createApiCall(() => {});
+      assert.strictEqual(typeof apiCall, 'function');
+    });
+  });
 });
 
 describe('Promise', () => {
@@ -350,7 +375,7 @@ describe('Promise', () => {
         assert.ok(Array.isArray(response));
         assert.strictEqual(response[0], 42);
         assert.ok(deadlineArg);
-        done();
+        return done();
       })
       .catch(done);
   });
@@ -380,7 +405,7 @@ describe('Promise', () => {
     const promise = (apiCall as any)(null);
     promise
       .then(() => {
-        done(new Error('should not reach'));
+        return done(new Error('should not reach'));
       })
       .catch((err: {code: number}) => {
         assert(err instanceof GoogleError);
@@ -420,7 +445,7 @@ describe('Promise', () => {
     const promise = (apiCall as any)(null);
     promise
       .then(() => {
-        done(new Error('should not reach'));
+        return done(new Error('should not reach'));
       })
       .catch(() => {
         assert(callCount < 4);
@@ -509,7 +534,7 @@ describe('retryable', () => {
         assert.strictEqual(resp[0], 1729);
         assert.strictEqual(toAttempt, 0);
         assert.ok(deadlineArg);
-        done();
+        return done();
       })
       .catch(done);
   });
@@ -534,7 +559,7 @@ describe('retryable', () => {
     const promise = apiCall({}, undefined);
     promise
       .then(() => {
-        done(new Error('should not reach'));
+        return done(new Error('should not reach'));
       })
       .catch((err: Error) => {
         assert(err instanceof Error);
@@ -795,6 +820,7 @@ describe('retryable', () => {
       })
       .then(() => {
         mockBuilder.verify();
+        return;
       });
   });
 
@@ -821,9 +847,9 @@ describe('retryable', () => {
       try {
         assert.strictEqual(gotHeaders.h1, 'val1');
         assert.strictEqual(gotHeaders.h2, 'val2');
-        done();
+        return done();
       } catch (err) {
-        done(err);
+        return done(err);
       }
     });
   });
diff --git a/core/packages/gax/test/unit/exports.ts b/core/packages/gax/test/unit/exports.ts
index 8132209b46d..fefa004f9fd 100644
--- a/core/packages/gax/test/unit/exports.ts
+++ b/core/packages/gax/test/unit/exports.ts
@@ -62,6 +62,9 @@ describe('exports', () => {
     it('exports protobufMinimal', () => {
       assert(typeof index.protobufMinimal === 'object');
     });
+    it('exports checkTelemetryEnabled', () => {
+      assert(typeof index.checkTelemetryEnabled === 'function');
+    });
   });
 
   describe('fallback', () => {
diff --git a/core/packages/gax/test/unit/gax.ts b/core/packages/gax/test/unit/gax.ts
index 214b3d07d46..d166ef98c03 100644
--- a/core/packages/gax/test/unit/gax.ts
+++ b/core/packages/gax/test/unit/gax.ts
@@ -198,4 +198,39 @@ describe('gax construct settings', () => {
     assert.strictEqual(backoff.maxRetryDelayMillis, 1000);
     assert.deepStrictEqual(settings.retry.retryCodes, [RETRY_DICT.code_c]);
   });
+
+  describe('CallSettings telemetry fields', () => {
+    it('defaults enableTelemetryTracing to undefined', () => {
+      const settings = new gax.CallSettings();
+      assert.strictEqual(settings.enableTelemetryTracing, undefined);
+    });
+
+    it('initializes enableTelemetryTracing', () => {
+      const settings = new gax.CallSettings({
+        enableTelemetryTracing: true,
+      });
+      assert.strictEqual(settings.enableTelemetryTracing, true);
+    });
+
+    it('merges enableTelemetryTracing', () => {
+      const settings = new gax.CallSettings({
+        enableTelemetryTracing: true,
+      });
+      const merged = settings.merge({
+        enableTelemetryTracing: false,
+      });
+      assert.strictEqual(merged.enableTelemetryTracing, false);
+    });
+
+    it('copies enableTelemetryTracing when merging with null/empty options', () => {
+      const settings = new gax.CallSettings({
+        enableTelemetryTracing: true,
+      });
+      const mergedNull = settings.merge(null);
+      assert.strictEqual(mergedNull.enableTelemetryTracing, true);
+
+      const mergedEmpty = settings.merge({});
+      assert.strictEqual(mergedEmpty.enableTelemetryTracing, true);
+    });
+  });
 });
diff --git a/core/packages/gax/test/unit/util.ts b/core/packages/gax/test/unit/util.ts
index 2a716fa2711..85be595496b 100644
--- a/core/packages/gax/test/unit/util.ts
+++ b/core/packages/gax/test/unit/util.ts
@@ -15,7 +15,7 @@
  */
 
 import assert from 'assert';
-import {describe, it} from 'mocha';
+import {afterEach, describe, it} from 'mocha';
 import {
   toCamelCase as snakeToCamelCase,
   camelToSnakeCase,
@@ -24,7 +24,10 @@ import {
   getProtoNameFromFullName,
   decodeProtobufAny,
   decodeAnyProtosInArray,
+  checkTelemetryEnabled,
+  StaticTraceContext,
 } from '../../src/util';
+import {CallSettings} from '../../src/gax';
 import * as protobuf from 'protobufjs';
 import protosJson from '../../protos/status.json';
 
@@ -196,4 +199,63 @@ describe('util.ts', () => {
       JSON.stringify([{reason: 'SERVICE_DISABLED'}]),
     );
   });
+
+  describe('checkTelemetryEnabled', () => {
+    afterEach(() => {
+      delete process.env.GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED;
+    });
+
+    const mockTelemetryInfo: StaticTraceContext = {
+      gcpClientService: 'test.googleapis.com',
+      gcpVersion: '1.0.0',
+      gcpRepo: 'googleapis/google-cloud-node',
+      gcpArtifact: 'google-cloud-test',
+    };
+
+    const mockSettings = new CallSettings({
+      enableTelemetryTracing: true,
+      otherArgs: {
+        internalTelemetryInfo: mockTelemetryInfo,
+      },
+    });
+
+    it('returns true when GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED=true and settings are configured', () => {
+      process.env.GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED = 'true';
+      assert.strictEqual(checkTelemetryEnabled(mockSettings), true);
+    });
+
+    it('returns false when GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED is not set', () => {
+      assert.strictEqual(checkTelemetryEnabled(mockSettings), false);
+    });
+
+    it('returns false when GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED is not "true"', () => {
+      process.env.GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED = 'false';
+      assert.strictEqual(checkTelemetryEnabled(mockSettings), false);
+    });
+
+    it('returns false when enableTelemetryTracing is not set on settings', () => {
+      process.env.GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED = 'true';
+      const noTracingSettings = new CallSettings({
+        otherArgs: {
+          internalTelemetryInfo: {
+            gcpClientService: 'test.googleapis.com',
+          },
+        },
+      });
+      assert.strictEqual(checkTelemetryEnabled(noTracingSettings), false);
+    });
+
+    it('returns false when internalTelemetryInfo is not set on settings', () => {
+      process.env.GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED = 'true';
+      const noInfoSettings = new CallSettings({
+        enableTelemetryTracing: true,
+      });
+      assert.strictEqual(checkTelemetryEnabled(noInfoSettings), false);
+    });
+
+    it('returns false when settings is undefined', () => {
+      process.env.GOOGLE_SDK_NODE_EXPERIMENTAL_O11Y_ENABLED = 'true';
+      assert.strictEqual(checkTelemetryEnabled(undefined), false);
+    });
+  });
 });