Hi @Duka1, let me see if I can help out here.
Your post has been translated to English as this is an International forum, please post any replies in English and it will be easier for me and other users to assist you.
I believe that the feature you are looking for is a feature called "Call waiting". If you have activated call waiting, you can handle multiple calls at the same time. When it is activated, you will be notified by a beep if you receive another call. Select to either accept the incoming call or decline it.
The person calling you will simply hear the dial tone and if you decide to decline the call, they will either hear the busy tone or be directed to your voicemail service, if supported and activated. To activate the Call Waiting-feature, please follow the steps below.
- Find and tap Phone > menu button (three vertical dots) > Settings > Calling accounts.
- Tap the account that you want to configure > Additional settings.
- To activate or deactivate call waiting, tap Call waiting.
Let me know if that helped and please return if I have misinterpreted your question in any way!
