Is it difficult to make a cell phone ( 4G ) ?

[Jan Audio]

Hi, i would like to know how simple or difficult it is to make a cell phone for 4G network ?
thanks

[Siwastaja]

All the magic is inside chips, in silicon design, both analog RF and digital logic.

So if you can get the chips, and if you can get the documentation - neither of which you as mere mortal can't - the rest isn't too difficult.

The chip design incorporates decades of wisdom from the brightest minds of this planet, however. No single person is able to recreate that.

[Jan Audio]

So you cant order those chips from mouser ?
Ohh, shocking.

[LaserSteve]

You can order a OEM module that takes a SIM card.  That is about it.

Steve

[Jan Audio]

There are many brands that make cell phones,
how do they all get the chips and info ?

[Gyro]

Because they have extremely close relationships with their suppliers when it comes to specifying chip functionality and buy vast quantities.  Obviously!

[Jan Audio]

I mean how do you start as new brand then ?
Bribe them ?

[Ice-Tea]

No, but you will need a convincing story and promise loads of volume.

[Jan Audio]

If you have no clue if it works for you, just buy in quantity, sounds risky.

[Ice-Tea]

I didn't say "buy loads" but "promise loads of volume". Contacting Broadcom asking for full disclosure for a 10k production run of "Ultra High Audio Grade cell phones" won't even cause a blip on their radar.

Contacting them with a convincing bussiness plan for 1M+ units a year will probably see you through the door.

[Gyro]

If you have no clue if it works for you, just buy in quantity, sounds risky.

If you have no clue whether it works for you, then trust me, you don't. It requires very significant investment development facilities and design staff for a start.

[Jan Audio]

Maybe aliexpress have them also.

[JohnnyMalaria]

If you have no clue if it works for you, just buy in quantity, sounds risky.

If you have no clue then perhaps the cell phone industry isn't the right one for you.

[Gyro]

@Jan Audio. You're just trolling.

[Ice-Tea]

Maybe aliexpress have them also.

Chips? Probably. Working chips? Perhaps.

Documentation? No.

[tszaboo]

I mean how do you start as new brand then ?
Bribe them ?

You can't buy chips. You would need to prove them, that you can pass GSMA FCC CE and other certifications before they would even consider selling anything to you. All this is like 100KEUR budget, if everything passes first try.
Buy a module. Most modules have either direct audio in/out or I2S. Putting together a phone to call is not that hard for an experienced engineer. For example page 157 below shows you how to make a phone.
https://www.u-blox.com/en/docs/UBX-13004618
But then you have a board that does nothing. Then you need to start antenna matching from almost DC to daylight. That can take a few days getting it right.
And then writing software. Which can be ridiculously complicated. The issue is not making a call, that is a few AT commands. Where the complexity comes from is network providers doing all kinds of crazy stuff. They do this for political reasons, backwards compatibility, network limitations, and so on. You want to roam in France, and you suddenly cannot connect to your preferred network. And the modem only tells you that you have some sort of unspecified error. You search the error, and there is like 1 forum post from 2011 from a guy who tried to do the same as you. Nothing is documented about these things. And this is just the tip of the iceberg.

[Kosmic]

The best way these days to play with the cell networks is with SDR. You don't need the cellphone chip. Just do everything in software!

With something like that for example: https://github.com/srsLTE/srsLTE

[Jan Audio]

Ok, it is not the 4G frequency i see, so it wont work i assume.
btw : i have no idea what it is.

[jonpaul]

Acess to Cellular chipsets is highly restricted due to security considerations.

You need to pay patent license fees and negotiate an agreement.

Finally FCC clearance is required with testing.

I would think the minimum to start is ~ 10-100M$.


Bon Chance,

Jon

[Kosmic]

Ok, it is not the 4G frequency i see, so it wont work i assume.
btw : i have no idea what it is.

4G is pretty vague. You need to decide which protocol/tech you want to support.

LTE == https://en.wikipedia.org/wiki/LTE_(telecommunication)#:~:text=In%20telecommunications%2C%20Long%2DTerm%20Evolution,together%20with%20core%20network%20improvements.

Frequency used and protocol are 2 different things. You could have a 5G link on 900Mhz if you wanted. Just going to be a bit slower.

[Jan Audio]

I dont know if the callcenter of my provider knows what 4G protocol they are using.
I also cant find it online.
Ok not so simple.

[Kosmic]

I dont know if the callcenter of my provider knows what 4G protocol they are using.
I also cant find it online.
Ok not so simple.

Normally you can find that information online. The protocols and frequency bands they are using. It's pretty standard stuff.

Your typical cellphone would support multiple frequencies and protocols though. You can find that in the specs of the phone.

[Monkeh]

Hi, i would like to know how simple or difficult it is to make a cell phone for 4G network ?
thanks

So far beyond your skillset it's not even remotely worth contemplating.

[Jan Audio]

O no not him again.

Finally FCC clearance is required with testing.

One thing i dont understand : if you use those parts, why is the testing still needed ?, they already tested those parts.

[Monkeh]

One thing i dont understand : if you use those parts, why is the testing still needed ?, they already tested those parts.

The individual components are not representative of the total design. There are many software settings, many possible mistakes in amplifier configuration, antenna design..