Hello. I wish you a good day!

I am a very new user on this forum and i am also new to the carrier.

I have a few questions about buying a cellphone on a monthly payment basis without tariff. 

This will be the very first time ill be buying a cellphone on a monthly payment contract.

1. I tried to understand all i could from the already mentioned information on the o2 website regarding this topic. Are there any charges other than the monthly amount, and the first time deposit, ill be paying for the phone? because the website says there is no interest in the monthly payment.
2. Will i be able to use any sim card with this tariff-free phone?
3. In case i want to end the contract early and pay the remaining amount upfront, will there be an early termination charge?

Looking forward to your reply, thank you and have a nice day!

edit o2_Manga: verschoben nach Englisch o2 Community: Mobile