Data going back to 1991 are available in .pdf, .txt and .wkn format. Electronic Market Data Book . E4 Annual review which includes several chapters on telecommunications and broadcast equipment. Provides factory sales and trade statistics for telephone sets, cordless and cellular phones, answering machines, modems, and facsimile equipment. Coverage is international in nature and, in some cases, provides at least 10 years of data.
Telecommunications is one of the industries they follow.
Multimedia Telecommunications Market Review and Forecast . Summary statistics are available at Telecom Industry Trade Statistics . Office of Telecommunications . U.S. Department of Commerce. Statistical Trends in Telephony .