A joint venture of Siemens AG and Nokia Corp., two large European technology firms, is denying reports that Iran uses its Web-monitoring technology to censor and spy on its citizens’ online activities. Nokia Siemens Networks said Monday that it has sold telecommunications systems to the Iranian government but that any built-in monitoring technology was for voice communications and not the Internet. “The lawful intercept capability is purely for local voice calls,” spokesman Ben Roome said in an interview. “We don’t know who may have provided other Internet technologies to Iran.”