Question about AVM FRITZ!Box 6850 5G International

I want to put a DATA + VOICE SIM card in the handset (regardless of the supplier). If I plug my analogue phone into the ANALOG port, will it work? - do I have my mobile phone number on the SIM card? Or do I have to take out a subscription with a Swiss VOIP provider? - I've also been told that I don't have to take an AVM handset for the telephony part? Thank you :)