Working with a commercial interiors drafting service is much like working with your in-house design team. It is essentially a repeating loop of you providing me with a markup or sketch as a scanned .PDF and I returning to you a .PDF and a .DWG drawing for you to review and comment. This loop repeats many times until we converge on a set of construction drawings.
Some clients prefer to work in AutoCAD, SketchUp, or Revit. In that case your team and I would synchronize our software tools so that the round trip of information becomes seamless. This usually happens when you have your in-house staff sharing the creation of construction drawings with me and we divide the work. In essence I would act as an overflow to your in-house design team.
If you have any questions, please feel free to email me at firstname.lastname@example.org