Use a cloud Android phone when your agent’s task lives in the UI: install a build, read the screen, tap through a flow and check the result. Use a physical device when the task depends on hardware, on device attestation or on performance that has to match a real handset. Mobilebox runs cloud Android phones self-serve and sets up real Android devices with you on an onboarding call.
What a physical device adds
Attestation is the clearest dividing line. In Google’s Play Integrity verdicts, MEETS_DEVICE_INTEGRITY means "the app is running on a genuine and certified Android device". The verdict is blank when the app is "not running on a physical device (such as an emulator that does not pass Google Play integrity checks)". An app that gates sign-in or payment on that verdict needs a device that earns it.
Hardware is the second. Android’s testing strategy guide notes that media players and camera apps "might depend on specific hardware features". Its example plan runs application tests on emulators plus one phone and one foldable, and release candidates on eight phones, a foldable and a tablet. The hardware device guide is direct: "Always test your Android app on a real device before releasing it to users."
A real device is not always a phone line
Check the exact feature with the vendor. AWS Device Farm runs tests on real devices, yet its FAQ says the devices "do not have carrier connections and cannot make phone calls or send SMS messages". It offers network shaping and a GPS override instead. "Physical" answers the attestation and hardware questions; it does not by itself answer the SIM question.
Choose by the task
| The task depends on | Cloud Android phone | Physical device |
|---|---|---|
| Installing an APK and reading its first screen | Fits | Also works, with more setup |
| A multi-step UI flow with a checkable outcome | Fits | Also works |
| Keeping a login between agent sessions | Park and resume | Depends on the lab’s reset rules |
| Play Integrity device verdicts | May not pass | Needed |
| Camera, sensors or release-grade performance | Not the right test | Needed |
| Calls or SMS | Not available on Mobilebox | Only if the device has carrier service |
Most agent work sits in the top rows. Move a check to hardware when a failure could only be explained by the device.
What the cloud phone gives your agent
Mobilebox runs cloud Android 14 phones (arm64). Your agent drives them over REST or a hosted MCP server: it observes the screen as numbered elements, then taps, types and swipes, installs APKs, and parks the phone to keep apps, data and logins. A ready phone costs $0.01 per minute. Google Play and SMS are not available, and apps with strict integrity checks may not run. The compatibility checklist helps you test that before you build a workflow on it. To connect an agent, start with the quickstart.
Real devices on Mobilebox
Real Android devices start with a 30-minute onboarding call. Until your setup is done, the API option device: "real" (reference) gives your agent a cloud Android phone, billed as cloud: treat what it returns as cloud evidence, not device evidence.
Hosted labs cover the physical half as well. Firebase Test Lab runs tests on real, production devices in a Google data center, and also offers Android emulators. AWS Device Farm offers remote access and automated runs on physical phones and tablets. Keep both results tied to the same build, and say which risk each one covered.
Sources reviewed on November 4, 2026.