The ThinkPad T480 as a Mobile Phone: Calls, SMS and Mobile Internet

Blogger Maroš Grego has shown that a ThinkPad T480 laptop can be used as a full-fledged mobile phone: taking calls, sending and receiving SMS, and browsing the mobile internet. As proof, he posted a video in which he answers an incoming call on his machine — one fitted, no less, with a keyboard from the anniversary “25 Year Edition.”

What's the catch

The T480 has long come with a SIM-card slot designed for LTE modems. There's just one problem: the PCM contacts that carry the audio are not physically connected. That's what keeps you from turning the laptop into a phone “out of the box.”

Getting around this limitation is made possible by the famous vulnerability in the Intel Management Engine. Thanks to it, you can install Libreboot in place of the stock firmware and, at the same time, lift the “whitelist” of approved wireless cards — and fit whatever modem you like.

A modem from the PinePhone

The author calls the Quectel EG25-G a good choice: this modem was used in the PinePhone and has therefore passed through the hands of a great many researchers. Inside it, as in most standalone modems in Android phones, runs its own ARM core with an Android system. There is an alternative firmware for it with a free user environment.

If you configure that firmware so that the modem registers with the system as a USB audio interface, then the audio of voice calls starts to be transmitted correctly. SMS and mobile internet, according to the author, work right away, with no additional trickery.

Not without some soldering

The main difficulties turned out to be purely mechanical. Versions of the Quectel EG25-G in the M.2 form factor that fit the T480 are rare and lack compatible antenna connectors. The author had to make adapter cables for the antennas — a job that, by his own admission, was extremely tedious. But in the end it all worked.

The author sums up his conclusion with a fair dose of irony: you can now safely throw out your smartphone and get by with just a laptop. And so that life doesn't feel too spartan, Android apps run natively on it through Waydroid.

The practical value of such a gadget is, of course, doubtful: not everyone will agree to carry a ThinkPad in their pocket instead of a phone. But the project is a vivid demonstration of what open firmware and the persistence of one person with a soldering iron can accomplish.

Source: Lobsters