The 155 is an old pattern that started in the 1940s. The originals were made in Germany and also the USA. I believe it was discontinued for a time in the late 90s and then brought back through the Boker Plus line as model BK-BO155. These were made in China. Just checked the Boker site and it looks like they're no longer offered, so yes may have been discontinued.
If you're looking for a similar knife, Case makes the Utility Hunter (model 00381) and Finn (model 00379). Both very similar patterns to the Boker 155.