This excerpt taken from the TI 20-F filed May 19, 2006.
The majority of non-current financial liabilities of the Telecom Italia Group consist of notes and bonds and their measurement at fair value can be easily determined using financial instruments which, because of their size and distribution among investors, are frequently traded on the markets (see Note 18Financial liabilities (current and non-current)). Where public trading data is not available, for other types of loans, the following assumptions were made:
Finally, the carrying value of most of the financial assets reasonably approximates their fair value as they are short term liquid financial investments.
Fair values (including interest accruals) of financial liabilities and assets at December 31, 2005 are set below: