The services of women helpline 181 was affected on Wednesday due to damage in underground telephone cables near Income Tax Office (ITO).
Officials said the Telecommunication department was working to restore the telephone lines.
"The repair work is being conducted on a war footing. It is expected that the helpline service would resume at the earliest," they said.
Delhi government had launched the 24-hour helpline a month ago to help women in distress following massive public protest in the wake of the December 16 gang-rape incident.
The helpline operates from Chief Minister Sheila Dikshit's office in Delhi Secretariat.