1. Dial the exit code: 00.
2. Dial the country code for Germany: 49.
3. Dial the mobile number of the person you are calling.
Here's an example:
You want to ring a mobile number in Germany that is 0123456789.
So you would dial:
00 49 123456789.
The international prefix will vary depending on your service provider. It could be 00 or + for example.