A telephone (or by extension email, web or SMS) service which offers help to those that call, either as an public emergency service or customer service.(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "helpline" in a sentence
"I called the helpline last month to see if there were any issues only to be told that the RPA wasn't obliged to pay me until 30 June."
"I called the helpline in the morning and asked them to reschedule it to any centre near Bhopal."
"I called the helpline on November 30 and they informed me the rescheduled date would be sent through either SMS or email."