Raspberry Pi Phone project

OK so I want to build a cell phone using a Raspberry Pi.
I'm not sure what module to get. Does anyone know. Some are advertised as GSM/GPRS and some as 4G/LTE.
I know GSM is the way to go but still confused when the description doesn't say they handle 4G/LTE.
And any suggestions on the best module to buy. Don't need blue tooth since the Pi already has that and has Wifi.
P.S. I usually buy my componets from Aliexpress.com. Slow delivery but cheaper price, good quality and selection.
Chuck LoweAsked:
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Shaun VermaakTechnical SpecialistCommented:
I would do it the way demonstrated in this article mainly because I have all the components and they are readily available
http://www.davidhunt.ie/piphone-a-raspberry-pi-based-smartphone/
Chuck LoweAuthor Commented:
@Shaun Vermaak
 That's the project that prompted me to start my own. It's from 2014 so it's 4 years old. Also there was one from a kid Tyler (can't remember last name). I will use them as foundations cause they worked and Tyler added SMS (texting) to his.

But my concern is with technology changes and cell phones (going to a very dangerous 5G. Dangerous for our bodies that is. That's another story) I want to be sure I'm using the latest and greatest. I just need to know the difference in GSM/RPRS vs. 4G, LTE etc.

As I read most phones today are GSM. CDMA has been phased out. But I want to pick the latest and correct for voice, text and data.

If I don't find a decent response on here I'll probably go with a similar product to the SIM900A (upgrade from the SIM900 in the other 2 projects) mentioned in this project

 https://circuitdigest.com/microcontroller-projects/raspberry-pi-phone-by-interfacing-gsm-module

It's fairly cheap. Under $30 here in the US. And I plan on first trying it with the Raspberry Pi Z W. I'd like to use SQLLite3 or some DBMS on it for the phone contacts. And of course Python 3 coding.
The aforementioned project uses an LCD instead of a touch screen so I'll use Tkinter or some Python Gui for the SMS with my touch screen for phone dial, text and Contacts.

So if anyone else has ant thoughts on this please feel free to let me know.

Thanks again.
Chuck LoweAuthor Commented:
I will close this and come back to it when I have more free time.

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Chuck LoweAuthor Commented:
No solution. Closing the question.
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