Connection problems or invalid MMI code

[TheEggMan]

None of the MMI codes I punch into my dial pad work. I keep getting the error "connection problems or invalid MMI code" 

Code Function
*#0*# Access diagnostics
*#011#Network details and serving cell information
*#0228#Battery status
*#0283#Loopback Test menu
*#0808#USB Setting
*#1234#Software version/ Model details
*#2663#Firmware details(Advanced)
*#7353#Quick test menu
*#9090#Advanced debugging tools
*#9900#SysDump
*#2683662#Service mode(Advanced)
*#34971539#Camera firmware details

I want to be able to utilise all of the above.

Samsung haven't been overly helpful on this matter and they keep fobbing me off to my phone network saying this is an issue on their side, but I disagree. These codes are coded into the device by Samsung, not my phone network. 

I have attempted everything online, to no avail 

[Paritosh]

I faced the same issue and solved after applying a YouTube suggestion. Dial *#21# , this will say "MMI code started" and a popup will come, click OK. After this step the problem should be fixed as it happened with my phone.

[JOD64]

What's the auto blocker?

[Anonymous User]

Android 14 ,Samsung default 

[LittleBottle]

I have issues connecting my Samsung S8 to iD 4G( using 3 Three network ) phone call functions. I used the MMI code provided by iD to connect to their network, but my phone was barred.
🙏

[Robyn09]

What if it don't work 

[Trey Keesling]

I have the same issue too

[IceLancer]

Hey ppl.

I solved the issue by simply using codes in Samsung proprietary app. Green Icon called phone. Not to be mistaken with white/blue google phone icon.

Typing code instantly shows screen. In my case i really needed to reset battery cycle count.
*#9900#