DLS50-26-12 Consultronics / Spirent DLS50/26-12 Wireline Simulator. The DLS50/26-12 can be used to test ISDN, DLC, DSL, HDSL, DDS and DSU etc. Manufacturer: Consultronics Consultronics / Spirent DLS50/26-12 Wireline Simulator. The DLS50/26-12 can be used to .