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| Qin F21 Pro with Dumbdroid |
最近入手了 Qin F21 Pro 按鍵式手機，幾年前曾看過 Jose Briones 的評論影片，後來也陸續在 r/dumbphones 瀏覽過相關分享，但是從不曾對這支手機感到興趣，直到 2025 年 10 月，Dumbdroid 的開發者 Michal Brzozowski 發布了一篇文章，介紹這個作業系統的基本資訊：
- Based on Android 14 (Andy Yan's LineageOS 21.0 GSI, to be precise)
- Optional Google Play Services and Play Store (the non-google version runs microg)
- Supports almost every Android app, besides those that require strong google play integrity.
- Built-in parental controls for app restriction and disabling app installation.
- Frequent updates with bug fixes and new features.
- Optimized for keypad controls, with Nokia-style navigation.
Qin F21 Pro with Dumbdroid Review
I recently picked up a Qin F21 Pro keypad phone. A few years ago I had watched Jose Briones' review video, and later browsed related posts on r/dumbphones, but I never felt particularly drawn to this device — until October 2025, when Dumbdroid developer Michal Brzozowski published a post introducing the operating system's basics:
- Based on Android 14 (Andy Yan's LineageOS 21.0 GSI, to be precise)
- Optional Google Play Services and Play Store (the non-Google version runs microG)
- Supports almost every Android app, besides those that require strong Google Play integrity
- Built-in parental controls for app restriction and disabling app installation
- Frequent updates with bug fixes and new features
- Optimized for keypad controls, with Nokia-style navigation
What is Dumbdroid? It's a LineageOS-based operating system, initially developed by Andy Yan for the Qin F21 Pro, and later customized by Swede Michal Brzozowski, who expanded support beyond the original F21 Pro to include the Qin F22 Pro, Doov R77 Pro, and R17 Pro, naming it Dumbdroid. Its defining features are the ability to choose whether to install Google Play Services and the Play Store, frequent system updates and new feature development, and a T9 keypad interface optimized to deliver a Nokia-like experience. All four of the supported devices share one thing in common: they all offer both touchscreen and physical keypad input.
None of these devices are particularly high-spec. In China, they're primarily marketed to students, with an emphasis on reducing phone addiction and supporting remote parental tracking and monitoring. They're also priced somewhat lower than typical touchscreen smartphones. The Qin F21 Pro was launched in 2022 and is still available today, typically selling for around TWD 3,000 to 4,000 depending on the version and platform.
I previously used the PUNKT MP02, which also ran a customized Android OS (aphyOS), so I understand firsthand how difficult it is to adapt a touch-based system into a keypad-driven interface. It was precisely this challenge that led to the MP02's downfall — despite its excellent hardware design, its software never caught up, and it was ultimately pushed out of the market.
I have an inexplicable fondness for small phones, likely shaped by my time with the MP02 — its sub-100g weight, compact form factor, and comfortable grip made me fall in love with its hardware. The Qin F21 Pro follows a traditional flat rectangular design and weighs similarly, so I picked one up and got ready to flash Dumbdroid onto it.
For the flashing process, I initially followed the official Dumbdroid instructions, but was unable to get it working on either Windows or Linux. I eventually succeeded using a bootable OS flashing method shared by Discord user @zmwa in the Duoqin Hacking community. If you're interested, it's worth a try — just make sure to back up your device beforehand. While Dumbdroid's website does sell pre-flashed R77 Pro units, demand has surged recently in Norway, so buying a device and flashing it yourself may be the faster route.
After nearly two weeks of use, here are my impressions split into two parts. On the software side, Dumbdroid runs remarkably stable — I've successfully completed two system updates. I don't use the phone heavily; it's mostly for calls and receiving Signal messages, and I'd conservatively estimate about three days of standby, roughly on par with my previous Pixel 8. The current version does not support WiFi Calling or wired Type-C headphones, and whether those will come in future updates remains to be seen.
On the hardware side, the F21 Pro's feel in hand is a notch below the MP02, but better than the Light Phone 3. The camera quality isn't great, but it lets me quickly add Signal devices — a far cry from the ordeal of adding a device through Pigeon (Signal) on the MP02 back in the day, so I'm satisfied. One complaint: the F21 Pro's ringtone volume is too low, and call quality isn't as clear as either the MP02 or the Light Phone 3.
As for the Light Phone 3 I had been using, since its software is still under development, I'll probably set it aside for a while and bring it back out once the feature set is more complete.