CHANDIGARH, July 23: Nearly 300 advice notes concerning release of City telephones are reported to be missing in the Chandigarh telecom circle.It is learnt that the advice notes were stolen and used for preparation of false documents. Fake documents with forged authorisations from telephone officials were prepared and passed on to the subordinate officials asking them to release telephone connections.While the exact number of such release of telephones is not clear, it is leant that 20 such cases have been detected already. Some of these telephones are being disconnected by the Department of Telecom. Meanwhile, a list of the missing advice notes is being prepared and department officials have been asked not to execute any works concerning such advice notes.