UK landline

I may be a unique case.  I work in the UK for a company based in Germany.  I am their only employee based outside of Germany.  I have the Swyx client on my PC and iPhone so that I can make calls as if I were in the office in Germany.  I would like to have a UK landline number on my outgoing CLI.  I know I can take out a virtual UK landline which can divert to my mobile or existing landline or even to the German office (with charges).  I can also use another softphone app to make calls.  I would like to keep using Swyx but with the UK identifier on outgoing calls,.  Is this possible?

Sorry I have no German language skills.