A Simple open-source Phone programmable with Arduino

It is not really a phone - it is more like a Wifi connected device which makes all calls over VOIP. There is no GSM connection and therefore no SIM etc. I like the project but calling this a phone is inaccurate.

If a GSM module is also included, this would be a lovely device to have. Also, would be nice to have a much larger screen.

I don't think that's fair. Phones used to be connected by wires, then there where a few satellite connected phones, and nowadays most are connected by cellular. But they're all phones because that's what we call a device used to connect and talk to people at long distance using a registry of numbers or names. This one connects using WiFi, which is unusual. But it has the same basic functionality of being a phone.

by your definition, my laptop is a phone too.

No, that's not the primary purpose of your laptop.