In order to do a Direct Dial from the softphone, you have to have a digital line assigned to the softphone. Now, almost all Users get a free Digital Line assigned to a softphone if you have a Digital Line assigned to a desk phone. Meaning, basically, that if you have a physical phone you get a free softphone.
One of the very few exceptions to this rule is for a German User. Because of Germanies address validation rules for VoIP phones, we cannot give a free Digital Line to the softphone. We have to validate a physical address for the phone which cannot be done on a free DL for a softphone.
In order for a German User to have a physical phone and a softphone that allows them to do a direct dial, you will have to purchase another full digital line and assign it to a softphone for each and every User. Unfortunately, this means that you will have to pay for 2 full Digital Line for each German User you want to have a phone and a softphone.