Yes, you can, if you have chosen one of the Internet options of the LMT Karte.
You can use your LMT Karte to call all numbers beginning with 800 unless their owners have asked to close them.
Yes, you will be able to keep your number when you substitute your LMT Karte with a post-paid LMT plan.
Yes, you can replace your SIM card at any LMT Customer Service Center.
If you would like to activate a lost LMT Karte, you will have to submit a request and provide the PIN 1.