@richard_degh What smartphone you exactly use? What postal code you have?

Hi @Joe Doe are you an employee of O2? 
I’ve used SIM card with both iPhone 12 Mini and 12 Pro. Frankfurt area. What does the information you requested say about not hearing a caller?

@richard_degh No. I am not an employee from o2. Only customer like you. (official o2 employee start with o2_ in the username) 

With IPhone 12 are in the moment big problems with the o2 network.

https://www.heise.de/news/iPhone-12-Telefonieprobleme-im-Netz-von-O2-dauern-an-5074957.html
 

@richard_degh . I have some information about your iPhone 12 issues.

The problem was first reported in the German forum 3 months ago

 link here     Its a  long thread with customer taking about the issues and O2 replying to comments and offering support suggestions. 

During theses months O2 offered discounts to the effected customer pending a fix.

To day as of right now there is a important update  from  @o2_Bianca in the German forum.

Bianca writes

“Hello @all,

a new info is just reaching me. To fix the limitations, only Carrier Bundle 45.1 is required.

The update is not mandatory.”

Update from 

Telefinica Deutschland . The problem of so-called "silent calls" has been fixed since last night. For this purpose, the network operator update 45.1 was rolled out by the manufacturer. If you are one of those affected, do the test and report gladly in the comments!

 Richard please check your iPhone for the update 

@Joe Doe

@ukguy

Thanks to both of you. I got the network firmware update with the iOS 14.4.1 update an hour ago. I have tried a call with a friend and problem seems resolved.

Hi @richard_degh, 

nice that @Joe Doe and @ukguy could already give you a solution. That´s great!

If you still have any further issues, just come back here to our English Community. 

Loving greetings,

Tobias