I forgot to mention that the field 'Prefix' in linphone settings accept numbers only - so you can't enter a normal dialplan there...
most of my phone numbers are stored with international prefix (like +49 xxx for german numbers).
However, on our sip server i need '0' to get the line, so I have to dial '00049xxx"
I asume that the setting "prefix" is used for this, and i tried different settings (0, 00049, 0049), but everytime I use a number out of the phonebook, linphone ignores this (wrong?) setting and dials without the leading '0'.
I would appreciate any hint on this,