The Imam Ali Missile Base is one of two Iranian silo missile bases. [1] Former Iranian President Khatami reportedly "ordered the production of 15 Shahab-3 missiles, to be deployed in underground bunkers near Khorramabad." [2] The underground silos present at the base appear to be large enough to host Shahab-3 missiles. [3] Iran also deploys mobile transporter erector-launchers, to be launched from pre-surveyed launch points, at the base. [4] The heavily guarded complex appears to consist of two main facilities, one of them a storage facility and the second an operational missile launch facility. [5]

Sources:
[1] Iran's Ballistic Missile Capabilities: A Net Assessment, The International Institute for Strategic Studies, (London, 2010), p.118.
[2] C. Bown, E. Jorgensen, G. Kampani and F. Wehling, "Nuclear- and Missile-Related Trade and Developments for Selected Countries, March-June 1999," The Nonproliferation Review, Fall 1999, p. 194.
[3] Iran's Ballistic Missile Capabilities: A Net Assessment, The International Institute for Strategic Studies, (London, 2010), p.119.
[4] Sean O' Connor, "Khorramabad Missile Silos," IMINT & Analysis, 25 February 2009, http://geiming.blogspot.com/2009/02/khorramabad-missile-silos.html.
[5] Sean O' Connor, "Khorramabad Missile Silos," IMINT & Analysis, 25 February 2009, http://geiming.blogspot.com/2009/02/khorramabad-missile-silos.html.