In order to meet the dual launch requirement for the Motorola IRIDIUM mobile satellite telecommunication network, whose primary, CALT developed the LM-2C/SD, a LM-2C with a newly-designed upper stage, the Smart Dispenser (SD). The payload fairing of the LM-2C/SD consists of nose dome, forward cone section and cylindrical section . The nose dome is made of non-metallic RF-transparent material. The cylindrical section and the forward cone section are of metallic honeycomb structure. LM-2C/SD launch vehicle sends the SD into an initial elliptical parking orbit, and at initial apogee the Dispenser's SRM (Solid Rocket Motor) fires to place the combination into a circular orbit.
Iridium was the anchor customer for the CZ-2C/SD, with two dummy payloads launched from the Taiyuan launch center on 01 September 1997, and two operational spacecraft on 08 December 1997. Additional pairs of Iridium spacecraft were launched in March and May 1998.