[2] At its height, Nortel accounted for more than a third of the total valuation of all companies listed on the Toronto Stock Exchange (TSX), employing 94,500 people worldwide.

[5][6] Alexander Graham Bell conceived the technical aspects of the telephone in July 1874, while residing with his parents at their farm in Tutela Heights, on the outskirts of Brantford, Ontario.

[32] Northern Telecom was, with Bell-Northern Research, in the early 1970s a part owner of MicroSystems International, a semiconductor manufacturer based in Nepean, outside Ottawa.

[39][40][41] As Nortel, the streamlined identity it adopted for its 100th anniversary in 1995, the company set out to dominate the burgeoning global market for public and private networks.

[43] Under the leadership of chief executive officer (CEO) John Roth, sales of optical equipment had been robust in the late 1990s, but the market was soon saturated.

[45][46][47] At its height, Nortel accounted for more than a third of the total valuation of all the companies listed on the Toronto Stock Exchange (TSX), employing 94,500 worldwide, with 25,900 in Canada alone.

His planned successor and chief operating officer (COO), Clarence Chandran, already on sick leave due to complications following his 1997 stabbing in Singapore,[50] decided to quit, however.

[52] Frank Dunn presided over a dramatic restructuring of Nortel, which included laying off two-thirds of its workforce (60,000 staff)[53] and writedowns of nearly US$16 billion in 2001 alone.This had some initial perceived success in turning the company around, with an unexpected return to profitability reported in the first quarter of 2003.

"[59] On April 28, 2004 amidst the accounting scandal, three of Nortel's top lieutenants—Douglas Beatty, CEO Frank Dunn and Michael Gollogly—were fired for financial mismanagement.

[66] After Dunn's firing, retired United States Admiral Bill Owens – at the time a member of the board of directors – was appointed interim CEO.

Gary Daichendt, the former Chief Operating Officer of Cisco Systems, was hired as president and COO, and was expected to succeed Owens as CEO.

Just three months later, Daichendt resigned after both his restructuring plan and his suggestion that Owens and Currie leave the company immediately were rejected by the board of directors.

[80] Rumours continued to persist of Nortel's poor financial health, amid the late 2000s recession, and its bids for government funds were turned down.

An extensive analysis by University of Ottawa professor Jonathan Calof and recollections of former Nortel executive Tim Dempsey have placed the blame mostly on strategic mistakes and poor management at the company.

Export Development Canada agreed to provide up to C$30 million in short-term financing through its existing credit support facility with Nortel.

[87] Nortel initially hoped to re-emerge from bankruptcy, implementing a retention bonus plan in an effort to retain its top executives during the restructuring period.

[113] Also in February, Nortel negotiated a $57 million deal to wind up the health care and other benefits provided to former Canadian employees.

[127][128] The last major asset of Nortel, approximately 6,000 patents and patent applications encompassing technologies such as wireless, wireless 4G, data networking, optical, voice, Internet, and semiconductors, was sold for $4.5 billion to a consortium including Apple, EMC, Ericsson, Microsoft, BlackBerry Limited, and Sony, pending American and Canadian court approval.

In April 2016, Nortel went back to court for a fresh round of legal arguments in a seven-year-old bankruptcy which cost creditors about $2 billion including attorney fees.

Past products included: In 2016, the Canadian Broadcasting Corporation reported that lawyers and accountants received CA$2.5 billion from Nortel's estate.

[139] In 2001 Nortel's director of information services Kathleen Peterson was found dead at the bottom of a staircase in her home in Durham, NC.

[141] After bankruptcy, Nortel's estate faced CA$300 million in claims to pay for environmental damage at various sites, including Belleville, Brockville, Kingston and London.

[145] Brian Shields, former chief security officer at Nortel, said his company was compromised in 2004 by China-based hackers; executive credentials were accessed remotely, and entire computers were taken over.

In 2008, Shields decided to approach an outside expert, who reported finding sophisticated malware in the company's machines and activities traced to Chinese IP addresses and discussions on a Mandarin Internet forum.

[146][154][155][156] On February 16, 2003, the Winnipeg Sun published an article criticising the Canadian Federal government for propping up "mega-loser Nortel" through Export Development Canada (EDC).

[158] The HWT was an unregistered trust maintained by Nortel to provide medical, dental, life insurance, long-term disability and survivor income and pension transition benefits.

According to the SEC, Dunn and three other financial officers began to fudge revenue by misusing "bill and hold" transactions starting "no later than September, 2000".

[165] In the middle of the decade several class-action lawsuits were filed against John Roth and others, by former employees who felt that their 401K company plans were depleted due to misrepresentation by the defendants.

The company eventually had employees in over 100 locations in the U.S. with R&D, software engineering, and sales centres in many states including California, Florida, Georgia, Illinois, Maryland, Massachusetts, North Carolina, Texas, and Virginia.

In the United States, Nortel's major R&D sites were in Research Triangle Park (North Carolina), Richardson (Texas), Billerica (Massachusetts), and Santa Clara.