This paper estimates demand elasticities for Turkish mobile telecommunications markets. In contrast to most other studies, firm-level data is used to estimate dynamic panel data models including instrumental variable techniques. Both short- and long-run elasticities are calculated, yielding a long-run price elasticity of -0.72 for the post-paid market and of -0.33 for the pre-paid market. The short-run price elasticity is estimated to be -0.36 for the post-paid market and -0.20 for the pre-paid market In addition, there is evidence of fixed-to-mobile traffic substitution for consumers who use pre-paid cards. (C) 2010 Elsevier Ltd. All rights reserved.