Fritz!Box sends the name that is entered into Fritz!Box' web interface. This overrides your local address book.
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In the following example the method update_offices_people_count won't be called when office_id changes, because it gets overwritten by the second line: after_save :update_offices...
office_id_changed? || trashed_changed? end Or, move the conditions into the callback. This also allows you test the conditions more easily using a unit test:
...DEBUG or MiniMagick.debug = true (deprecated) before the processing happens. This will print all ImageMagick calls to stdout and you can get an idea where the problem is coming from.