VoLTE Toggle (com.xcl.volte)

English | 中文

Enable VoLTE / VoNR / 5G SA for mainland China carrier SIMs (China Mobile, China Unicom, China Telecom) on Google Pixel. No root, no PC.

在 Google Pixel 上一键为中国大陆运营商卡（移动 / 联通 / 电信）开启 VoLTE / VoNR / 5G SA。不需要 root，不需要电脑。

📦 Download / 下载：Releases → volte-toggle.apk

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English

The problem

Google Pixel phones usually ship without VoLTE / VoNR enabled in the carrier config for China Mobile, China Unicom and China Telecom. Symptoms:

• Calls drop to 3G/2G, or fail on 4G/5G.
• There's no VoLTE / HD icon.
• You can't make calls on 5G.

These switches live in the system's CarrierConfig. Normally only the system or the carrier can change them. This app uses a local debugging channel from the phone to itself to override them with limited, debug-level privileges.

How it works

• Android doesn't let regular third-party apps write carrier config. That needs system-level permission such as MODIFY_PHONE_STATE.
• The app bundles an ADB client (kadb). It connects to the phone itself over the Wireless debugging loopback port and launches the app's own instrumentation with shell privileges.
• The instrumentation runs in the app's own process. It uses UiAutomation to temporarily adopt shell permissions, then calls CarrierConfigManager.overrideConfig(subId, bundle).
• The override is non-persistent, because that's the only mode Android allows for non-system callers. So it's lost on reboot and must be re-applied. That's what the "Re-apply after boot" option is for.
• Afterwards it calls TelephonyManager.resetIms(slot), so IMS re-registers immediately and the VoLTE icon appears.

Keys written

• VoLTE switches: carrier_volte_available_bool, enhanced_4g_lte_on_by_default_bool, carrier_volte_provisioned_bool and related keys.
• Optional:
  • vonr_enabled_bool for VoNR (5G calling)
  • carrier_nr_availabilities_int_array for 5G SA
  • the four VoWiFi keys

Turning a SIM off clears the override and restores the carrier defaults.

Usage

① First-time setup (once only)

1. Turn on Wi-Fi and connect to a network.

   ⚠️ Wireless debugging only works while Wi-Fi is connected. This step is required.

2. Enable Developer options: Settings → About phone → tap "Build number" 7 times until you see "You are now a developer".
3. Enable Wireless debugging: Settings → System → Developer options → Wireless debugging. Turn it on and keep it on.
4. Back in the app, tap Start pairing in the ADB channel card. Enter the 6-digit pairing code shown by the system into the notification and send it. Once it shows Ready, pairing is done. The key is remembered, so you don't need to pair again.

② Daily use

1. Make sure the ADB channel shows Ready. If it's unavailable, Wi-Fi or Wireless debugging is usually off.
2. Flip the VoLTE switch of a SIM to turn it on or off.
3. To also enable VoNR / 5G SA / VoWiFi, tick them under Options, then flip that SIM's switch again to write them.
4. The override is lost after a reboot. Flip the switch again, or tick Re-apply after boot to replay it automatically.

The "How to use" card at the top of the app is collapsed by default. Tap it to see these steps.

The UI defaults to English. Use the language button at the top right to switch between English / 简体中文 / 繁體中文 / 日本語 / 한국어 / Русский / Español / Français / Deutsch / Português. The choice is remembered.

Build

./build.sh          # produces volte-toggle.apk

The build doesn't use Gradle. It runs aapt2 → javac → d8 → package jni → zipalign → apksigner (debug key).

Dependencies live in libs/ as jars: kadb, okio, kotlin-stdlib, kotlinx-coroutines, BouncyCastle, spake2, hiddenapibypass. UI strings are in res/values*/strings.xml.

Known limitations

• Wireless debugging doesn't start when Wi-Fi is off, so the app can't reach its own ADB channel.
• The override must be replayed after every reboot (a system limitation). Use "Re-apply after boot" together with Wireless debugging.
• Re-apply after a system OTA update.
• Results depend on carrier and device model. Tested on Pixel 10 + China Unicom. Reports for other combinations are welcome via Issues.
• PairReceiver is exported so it's easy to trigger from adb while debugging. Set it to false in the manifest if that concerns you.

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中文

解决什么问题

Google Pixel 出厂的运营商配置里，往往没有为国内三大运营商打开 VoLTE / VoNR。常见表现：

• 打电话要掉到 3G/2G，或者 4G/5G 下打不出去。
• 没有 VoLTE 图标。
• 5G 下无法通话。

这些开关由系统的「运营商配置（CarrierConfig）」控制，正常只有系统或运营商能改。本应用用一条手机连自己的本地调试通道，以受限的调试身份把这些开关覆盖打开。

原理（简述）

• Android 不允许普通第三方应用写运营商配置，写入需要 MODIFY_PHONE_STATE 这类系统级授权。
• 本应用内置一个 ADB 客户端（kadb），通过无线调试的本机回环端口连上手机自己，以 shell 调试身份启动应用自带的 instrumentation。
• instrumentation 跑在本应用自己的进程里，借 UiAutomation 临时取得 shell 的授权，再调用系统的 CarrierConfigManager.overrideConfig(subId, bundle) 覆盖运营商配置。
• 系统对第三方只放开非持久化的覆盖方式，所以重启后覆盖会丢失，需要重新应用一次。界面上「开机后自动重新应用」选项就是为此准备的。
• 写完后调用 TelephonyManager.resetIms(slot) 让 IMS 立即重新注册，VoLTE 图标随即出现。

写入的键

• VoLTE 开关：carrier_volte_available_bool、enhanced_4g_lte_on_by_default_bool、carrier_volte_provisioned_bool 等一组相关的键。
• 可选：
  • vonr_enabled_bool（VoNR / 5G 通话）
  • carrier_nr_availabilities_int_array（5G SA）
  • VoWiFi 相关的四个键

关闭时会清空覆盖，回到运营商默认配置。

使用步骤

① 首次准备（只需做一次）

1. 打开 Wi-Fi 并连上网络。

   ⚠️ 无线调试只有在 Wi-Fi 连着时才工作，这一步必须做。

2. 打开「开发者选项」：设置 → 关于手机 → 连续点 7 下「版本号」，看到「已处于开发者模式」即可。
3. 打开「无线调试」：设置 → 系统 → 开发者选项 → 无线调试，打开并保持打开。
4. 回到应用，在「ADB 通道」卡片点「开始配对」，按提示把系统弹出的 6 位配对码填进通知里发送。 看到「已就绪」就配对完成，密钥会被系统记住，以后不用再配。

② 日常使用

1. 确认「ADB 通道」显示「已就绪」（若不可用，多半是 Wi-Fi 或无线调试没开）。
2. 拨动对应 SIM 卡的「VoLTE」开关，即可开启或关闭。
3. 想同时开 VoNR / 5G SA / VoWiFi：先在「选项」里勾选，再重新拨一次该 SIM 的开关才会写入。
4. 手机重启后覆盖会失效：回到应用重新拨一次开关，或勾选「开机后自动重新应用」让它自动重新应用。

应用主界面顶部的「使用步骤」卡片默认折叠，点一下即可展开查看以上步骤。

界面默认英文（English），点右上角的语言按钮可从列表切换：English / 简体中文 / 繁體中文 / 日本語 / 한국어 / Русский / Español / Français / Deutsch / Português，选择会被记住。

构建

./build.sh          # 产出 volte-toggle.apk

构建不用 Gradle，流程是 aapt2 → javac → d8 → 打包 jni → zipalign → apksigner（debug key）。

依赖以 jar 形式放在 libs/：kadb、okio、kotlin-stdlib、kotlinx-coroutines、BouncyCastle、spake2、hiddenapibypass。界面文案在 res/values*/strings.xml。

已知限制

• Wi-Fi 关掉时无线调试不启动，应用就连不上自己的 ADB 通道。
• 重启后必须重新应用（系统限制），可以靠「开机后自动重新应用」配合无线调试。
• 系统 OTA 升级后要重新应用。
• 能否成功取决于运营商与机型，目前在 Pixel 10 + 中国联通上测试通过。欢迎在 Issues 里反馈其他组合的结果。
• PairReceiver 设为 exported，是为了方便调试时用 adb 触发；介意的话可以在 manifest 里改成 false。

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License

MIT © Charlie