The Speedtest.net research, which ranks 124 countries, shows that Ireland has the slowest mobile service of any EU country.
The survey is based on feedback from tens of thousands of phones across the country.
It ranks Ireland 64th out of 124 industrialised nations, slightly behind Myanmar and Ecuador and just ahead of Honduras and Tunisia.
It comes after a promised map to identify mobile blackspots across the country was deferred until next year by the telecoms regulator, with the Government shifting responsibility for fixing the issue onto local government agencies and future State-backed task forces.
Irish telecoms licences do not require operators to cover a majority of the country, instead stipulating only that a majority of the population – based in cities and major towns – get a signal. This leaves large areas of the country with low-quality, low-speed mobile coverage.
The Speedtest survey confirms that this has left Ireland with mobile data speeds half that of poorer EU countries such as Bulgaria or Lithuania and less than a third of the average signal quality found in countries such as Norway and Iceland.
The problem is compounded by an admission from the telecoms regulator that it does not know where many of the country’s black spots are. This is due to limited testing ability across Ireland, which require significant manual resources.
Instead, it is preparing an estimated blackspot map based on a data-collaboration exercise with mobile operators. This was due to be published in 2018 but will not now appear until 2019, according to a spokesman for the regulator.
However, three of the top five performing countries in the Speedtest are Norway, Australia and Canada, with significantly lower population densities than Ireland.
A spokeswoman for Three said the availability of more mobile spectrum would help Ireland to improve its comparative position.
Among the four top carriers in Ireland, Vodafone makes its mark with the highest Speed Score in the country at 24.33.