Huawei p20 problem skype and normal call?

I use the paid Skype, so I can call abroad on mobile phone (not as you know otherwise with a skype program).

During my Skype call, I sometimes receive "normal" calls at the same time. This will automatically stop my Skype call. That annoys. I would like that in such situations my status with the second caller sounds busy

For this you would have to reprogram your ROM, because the "normal" telephoning is firmly anchored in the system and thus preceded.