我尝试在Android / iOS上运行launch(“tel://214324234”)，效果很好。您需要安装软件包url_launcher并将其导入 import it

import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher.dart';

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      home: new Home(),
    );
  }
}

class Home extends StatelessWidget {
  Home({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) => new Scaffold(
        appBar: new AppBar(
          title: new Text("View"),
        ),
        body: new Center(
          child: new FlatButton(
              onPressed: () => launch("tel://21213123123"),
              child: new Text("Call me")),
        ),
      );
}

void main() {
  runApp(
    new MyApp(),
  );
}

您也可以导入它import ‘package:url_launcher/url_launcher.dart’ as UrlLauncher;，然后使用UrlLauncher.launch(“tel://21213123123”)

确保在pubspec.yaml文件的依赖项部分中包含一个条目：url_launcher：^ 1.0.21.0.2