In 1996, the inventor received an award from the World Intellectual Property Organisation and a year later - after a five-year wait - he finally secured a patent in his homeland.

He then approached domestic mobile phone operators to claim his rights to royalties - and ran into a wall.

"One of the companies told me 'Go to court, maybe your great-grandchildren will collect something'," the he said. "So I decided to defend the rights of my great-grandchildren."

Over the years, BIMA was modified and named caller ID. But, despite repeated efforts, Nicolai was unable to secure the rights to the new name, causing him to lose out on millions of dollars.

"The financial prejudice caused is shameful. It's a crime against the state, because it affects the equity of not only an individual but of a country," he fumed.

Home to 194 million people, Brazil has more than 250 million mobile phone lines in use and each operator charges a monthly average of US$5 for caller ID service, according to Nicolai's lawyer Luis Felipe Belmonte.

Nicolai has filed lawsuits against leading cellular operators Claro, owned by Mexican telecom magnate Carlos Slim, as well as Vivo, owned by the Spanish group Telefonica.

Due to debts that almost left him homeless, he was forced to accept a settlement with Claro, which agreed to pay him only 0.25 per cent of his request.

The undisclosed proceeds enabled Nicolai to buy a upmarket house in Brasilia, as well as a new Mercedes. Now he hopes to collect more from other lawsuits.

In Brazil, registering a patent costs up to US$1,500 and takes an average of five years and eight months, compared with four years in the US.