add ServiceExtensionContext.startAbilityByCall api

Signed-off-by: NHuangXW <huangxinwei4@huawei.com>

zh-cn/application-dev/reference/apis/js-apis-service-extension-context.md

@@ -688,4 +688,42 @@ disconnectAbility(connection: number): Promise<void>;
   }).catch((error) => {
       console.log('failed:' + JSON.stringify(error));
   });
-  ```
\ No newline at end of file
+  ```
+
+## ServiceExtensionContext.startAbilityByCall
+
+startAbilityByCall(want: Want): Promise<Caller>;
+
+将指定Ability拉起到后台并获取其Caller通信接口，拉起方可使用Caller与被拉起的Ability进行通信。
+
+**系统能力**：SystemCapability.Ability.AbilityRuntime.Core
+
+**参数：**
+
+| 参数名 | 类型 | 必填 | 说明 |
+| -------- | -------- | -------- | -------- |
+| want | [Want](js-apis-application-Want.md) | 是 | 传入需要启动的ability的信息，包含ability名称、模块名、包名、设备ID，设备ID缺省或为空表示启动本地ability。 |
+
+**返回值：**
+
+| 类型 | 说明 |
+| -------- | -------- |
+| Promise<Caller> | 获取要通讯的caller对象。 |
+
+**示例：**
+
+  ```js
+  let caller = undefined;
+  this.context.startAbilityByCall({
+      bundleName: "com.example.myservice",
+      moduleName: "entry",
+      abilityName: "MainAbility",
+      deviceId: ""
+  }).then((obj) => {
+      caller = obj;
+      console.log('Caller GetCaller Get ' + caller);
+  }).catch((e) => {
+      console.log('Caller GetCaller error ' + e);
+  });
+  ```
+  
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