Plug in an EG25-G USB module. It has good driver suppport on linux as this is the same modem that's in the pinephone.

I'm actually working on this right now. It also gives you GPS.

That's the gnome dialer, yeah.

it's incredibly repairable. I still use the t480 for modern workloads because I've been able to switch out the battery, the fan, the keyboard with fairly abundant aftermarket parts.

Nice, I know these mainly had a spare NVMe slot right next to the WiFi, in case you had the optional WWAN adapter, and the essential SIM card holder itself is also there already regardless. The separate unused (apparently non-standardized) cellular antenna connectors are also there and taped off from the factory otherwise.

I would have never imagined that the Lenovo WWAN approach would not even support audio calling, good findings and excellent workaround :)

What I did was use a 2242 size NVMe SSD in that WWAN slot for extra storage, plugged in right next to the standard Wifi card.

Unfortunately I can not get this 500GB NVMe SSD to boot in the Lenovo WWAN slot, even though it works good in a regular NVMe SSD position. Even with functional boot files on the main working SSD which point to the proven OS on the NVMe in the WWAN slot.

Still good for additional SSD storage at least.

And it's good to know you figured out how to get WWAN calling working better than new on an older laptop, that's hacking that non-tech people can see how worthwhile it is :)

Great hack! Is it possible to use a Bluetooth headset?

Supposedly it's for FCC compliance. Makes perfect sense if you believe it, but I'm not super convinced.

Yes, whoever can shrink this down to the size of something that would fit in your pocket would make a killing. Imagine not only being able to make phone calls, but use productivity software and even browse the internet.

That modem or a few others can be used with some of the small SBCs, which have a smartphone size or even a smaller size.

If you connect then to some battery pack with a USB charger, you have a mobile solution, though one more cumbersome than a real smartphone.