Orange boss Stephane Richard came under political pressure today after a network outage at France's biggest telecoms firm prevented emergency calls for several hours.
French President Emmanuel Macron said he was "very concerned" by the incident.
Health minister Olivier Véran said it was too soon to say whether there was any link between the outage and three to four deaths recorded during the period.
The disruption to emergency phone services, which began yesterday afternoon, eased overnight but some minor issues still remained this morning, Veran told reporters.
"The situation is under control as we speak. All traffic on the emergency numbers is normal on the whole national territory," Richard said on French channel TF1, reiterating his apologies to those affected.
He had earlier been summoned by Interior Minister Gerald Darmanin, who called the glitch "serious and unacceptable".
The outage comes a day after a French prosecutor told judges of the Paris appeals court that Richard should face three years in jail for his alleged involvement in a disputed compensation payment made by the state in 2008.
The minister for digital affairs, Cedric O, said the state, which is Orange's biggest shareholder, will launch an investigation into the causes of the outage, which Orange said sporadically hit calls to emergency services in several regions.
Orange France chief Fabienne Dulac said that 20% of calls to emergency services failed on average, prompting French authorities to hastily put in place alternative emergency numbers that they publicised on social media.
Richard told TF1 he did not yet know the exact cause of the outage, but it was "most likely" due to a software failure in a critical network equipment responsible for routing all incoming calls from landline or mobile phones to emergency numbers.
Orange's boss said that for a yet unknown reason, all six redundant sites which the infrastructure relies on broke down at the same time.
He ruled out that the cause of the glitch was due to a cyberattack.
French rivals SFR and Bouygues Telecom said on Twitter that some of calls to fixed lines, beyond the ones made to emergency calls, had also been affected by the outage.
