The French health minister has said it is too soon to say whether a number of reported deaths were the result of a network outage that disrupted the number for the emergency services.
The outage on Wednesday left people unable to reach help for hours.
Health minister Olivier Véran said three or four deaths had been registered nationwide, but added that it was "too soon to draw conclusions".
He promised a "full report on the human consequences" of the outage.
Stéphane Richard, CEO of Orange, said he had met with government officials and the situation was "now stabilised".
"The Orange group apologises to those who have been affected in recent hours," he tweeted.
French government sources posted alternative emergency numbers online after the problems began.
Issues with the network first started at 18:00 local time (16:00 GMT) on Wednesday.
Dr François Braun, president of the emergency medical services provider Samu-Urgences, told BFM television channel that "one in three calls, one in two depending on location, could not be completed".
Problems emerged across the country but were particularly bad around Paris and the regions of Hauts-de-France in the north and the Grand-Est (east), he said.
As yet the cause of the problems remains unclear.
Orange told the AFP news agency that a "technical incident on a router" had disrupted voice over internet calls in some regions, and Mr Richard told channel TF1 it was not the result of an attack, instead saying it was likely a "software failure".
On Thursday morning Mr Darmanin criticised the "serious and unacceptable malfunctions".
He said at a press conference that a person in the Morbihan region in northwest France who suffered from a heart condition reportedly died after failing to put through a call to emergency services.
While it is not clear the death was directly caused by the outage, "what is beyond doubt is that people have told us that they tried calling several times and that they couldn't get an operator immediately," he said.
Two people with heart conditions in the overseas department of Réunion were also reported to have died.
President Emmanuel Macron said he was "very concerned" about the situation.
Orange France head Fabienne Dulac tweeted that their teams were still watching the situation and were "fully mobilised to ensure a return to normality".
In 2019 the Netherlands suffered its largest telecoms outage in years, with the emergency service number 112 knocked out across the country. The authorities advised people to go directly to hospitals, or to police and fire stations if they needed emergency help.
https://www.bbc.com/news/world-europe-57341526
